As the title implies, I am looking for thoughts/opinions on methods for getting a bit more power out of my 998 engine. I find running with highway traffic at 4K rpm for much time is tiring on me, though necessary for getting in/out of San Antonio. There are also a few hills that Bruce and I go over on our drives to area C&C events where I still lose significant momentum on the uphill.
The engine currently runs very nicely: has good oil pressure, does not overheat, gets me 30 - 33 mpg regularly. The transmission/differential is currently set up such that 4K rpm is 70 mph (3.1 final drive, but non-standard drop gears make it act like a 3.2 final drive)
The engine spec as it is currently: stock pistons and cam; alloy intake manifold supporting a single HS-4 carb with a K&N filter in a modified stock air box; LCB exhaust; Mini Sport "Stage-3" 998 head with mild porting and bigger valves; forged 1.4:1 ratio rocker arm set. The head and rockers were done to boost the power slightly from stock when I changed the final drive to the current setup.
What I would like to do is add more power so I can change the final drive again to either a 2.95 or 2.76 to lower the rpm more when doing highway speeds while still having sufficient power/torque for the winding hill country backroads.
The approaches I know of are: 1) upgrade to a 1275 based engine; 2) overbore and change the cam in the current 998; or 3) add a turbo kit to the existing spec.
Please chime in with your thoughts, pros/cons of the above approaches, any other alternative approaches.
1275 motor/gearbox would be my first choice because it's all bolt in. Turbo to the existing engine would be second choice because kits exist that again are (supposedly) bolt on stuff, but spendy ($5K+).
I run a 2:76 in my green Mini, 70 mph is about 3300 rpm, 75-80 is 34-3600 rpm. I only have to downshift to 3rd if it's a really steep hill or if I'm at altitude (Colorado Mtns)
I like turbo motors in general, don't know what to expect from the Jet motors kit on a 998, but the mods you've already done will help quite a bit, I would call Jeremy and see what he says.
I had planned on trying to speak with Jeremy at Jet Motors about their kit on a 998.
The 1275 option is at least as spendy as the turbo kit and it leaves me with the 998 still sitting around. Being in an apartment with detached garage makes storing things like an extra motor a bit iffy.
With all the work you have already done to the 998 engine I think I'd lean toward adding the turbo. Expensive but a 1275 upgrade will be as well. I suppose the advantage of the 1275 upgrade is the potential to sell the 998 to recoup some cost, but I don't know what the demand is for such things. Generally speaking if someone is going to buy an entire engine, its likely going to be of the 1275 variety.
Quote from: cstudep on September 06, 2026, 10:33:56 AMWith all the work you have already done to the 998 engine I think I'd lean toward adding the turbo. Expensive but a 1275 upgrade will be as well. I suppose the advantage of the 1275 upgrade is the potential to sell the 998 to recoup some cost, but I don't know what the demand is for such things. Generally speaking if someone is going to buy an entire engine, its likely going to be of the 1275 variety.
Those were some of my thoughts as well. I am also inclined to think the cost of rebuilding/enhancing the 998 (non-turbo approach) will likely be about the same as the turbo kit (pistons, rings, bearings, cam, machine shop work). I am not really into the Honda engine swaps and those tend to be spendy as well.
Yeah the Honda swaps are pretty spendy these days, probably the most expensive option actually. Just a worn out v-tec with transmission is getting pretty costly these days.
If you have a small bore stage 3 head with bigger valves you really need the cam to go with it. You might actually be a bit soggy down low with a stock cam on a performance head with bigger valves, though the 1.4s will help a little. Adding a nice street cam like a 266 or evo1, both would work great with 1.4 rockers, simultaneously going taller on the gears will make it feel equally "slow". You'll utilize 3rd gear a lot to pull hills. 3.1 or your 3.2 is a great compromise as is for doing highway speeds. To run a 2.76 in my humble opinion takes a large bore with power or better yet a turbo. I'm not a fan of taller gears because it's just lazy feeling to me in a mini. I still want a 5 speed for the best of both worlds. Also what's your compression ratio? Bump it up to about 10:1 with the cams listed above. If you're running low compression right now that alone will liven it up.
I am trying to keep cost effectiveness and ease of implementation in mind with this latest effort.
The goal is to have an engine that will confidently pull hills while providing decent highway capability/comfort and retain reasonable reliability.
One of the current issues is the non-standard drop gears. They shift the effective behavior of the final drive down one rating. Examples: the originally installed 3.44 set acted like a 3.76; the currently installed 3.105 set acts like a 3.2. If I install a 2.95, it will act like a 3.1 and installing a 2.76 will act like a 2.95.
I did not know it had the non-standard drop gears until after the change to the 3.1 final drive when I did not get the expected 3.1 behavior I really wanted. The performance of the current setup is basically adequate, but really needs just a little more "grunt" for the hills based on having the current configuration for a few years. The better highway behavior would be a nice addition.
To get the originally desired 3.1 behavior, I need to either change the drop gears to standard (1:1), or put in a 2.95. Either of which will mean the extra "grunt" will become more necessary. Thus this discussion for reasoable ways to achieve the desired results ("grunt" for hills and comfort for highways).
All that said, as far as I know it is still the factory 9.4 compression of the latter series 998s.
Is it possible to just change the cam without totally gutting the insides of the block?
To get what you want will take time and money is all. Dropping in a turn key 1275+ power house with a 2.95 or 3.10 would be the easiest way.
If you do tear down what you have, get the 1098 crank, add the cam, measure measure and triple measure deck heights, chamber volumes, piston dish volume, ect to know exactly what your compression ratio is. If you do a basic compression test you'll have a rough idea what you currently have. Tosssing on a stage 3 head may have a radically different chamber volume than stock. These details matter.
Are the connecting rods the same between a 998 and 1098?
Yes it's the stroker crank for a 998, so there may need to be thicker gasket and or block decking required to get proper deck height for piston to head clearance. Or you figure out what rods make it perfect without needing thicker head gaskets or block decking. Benefits are low end torque increase where you want it.
So I would have to tear it all apart in order to determine what may be needed before ordering parts?
Kind of something I was hoping to avoid if possible. But, that is why I started this thread - to get input and find out what sort of effort I would be facing.
You'd mock it up and see where the pistons top out at. Same as what I'm doing on a vw type 1 motor build with stroker crank, C height pistons, and 5.7" rods. You need to re-ring and dingle ball hone at minimum. If there is a lip/ledge on the cylinder wall then you're looking at a bore up at that point. But this is all part of the process.
No matter what you do with the gearing you're still only going to make about 40-45 hp with a 998, it's not enough to pull hills in 4th. A 1275 will make more torque and with a 3.0 will be in the sweet spot at highway speeds.
Dan's version with the 1098 crank will give it good torque, but you're talking about a total rebuild.
If you can find a guy with a Vtec removed 1275 you'd be in good shape.
Either that or go turbo - that will give you the torque to pull hills and the taller gears.
It's been forever since I read this but should explain it.
https://www.calverst.com/technical-info/engine-1098-initial-tuning-potential/
Thanks for the link. I will read it through a bit later for educational reasons.
As for this engine project, I think attempting to convert my 998 to a 1098 is beyond the intended scope.
I called Dave C. (MiniDave) and had a good discussion with him about the endeavor and have a better understanding of some of the approaches under discussion. I need some absorption time, but I think I may have a target approach in mind now.
Thanks to all that have contributed so far. The discussion does remain open to contributions.
I went out and did a compression test today for a current reference:
#1 - 152 psi
#2 - 152 psi
#3 - 145 psi
#4 - 152 psi
The plugs were all even in color - a light brown/tan on a set of NGK BP6ES plugs.
Quote from: MPlayle on September 08, 2026, 10:08:29 AMI went out and did a compression test today for a current reference:
#1 - 152 psi
#2 - 152 psi
#3 - 145 psi
#4 - 152 psi
The plugs were all even in color - a light brown/tan on a set of NGK BP6ES plugs.
Using my engine build app, and what A+998 specs I quickly found online, so correct any numbers if I got bad info, gives you about 8:5:1 compression around 155psi cranking
That is about what I expected the CR to be. The engine is a 99HG31 series which online searches did not explicitly indicate the CR for. The searches I did indicated standard 998s had 8.5 and the high-compression was 9.4. I expected this one to be more towards the standard 8.5 which Dan's calculations confirm.
More info with that in mind and I realize building a motor in your apartment is out of your scope. Taking that 8:5 ratio add the stroker crank and you get 9:3 compression. A size up on the pistons gives 9:4. A worked 1110cc motor will make more power than a clapped out stock 1275 from a v tec swap. Change the drop gears to get a 3:1.
Or, with that low of compression ratio, a bolt on turbo kit would be perfect..... :great:
Get more HP but more importantly, more torque - especially at lower RPM, which lets you run those taller gears for less noise on long highway runs.
OR.......just leave it alone and use third gear up those hills and let it wind out - it's good for it to do that once in a while. Dan had no problem keeping up with us 1275's with his 998 Mini on everything except a long uphill run, once over the crest he was right there with us again.
It would be a good candidate for a turbo at 8:5. But it needs to be tuned properly or you'll for sure be rebuilding it in your apartment.
Just to muddy up the waters a bit more :grin: I have a 1098 (1100?) I might be willing to sell. Dave and Dan are both quite familiar with it since that is where it came from. I really probably need to clear some stuff out anyway and I am not sure I will ever use it since I have a few 1275 motors I can rebuild.
You could put your head and what not on it and basically accomplish what Dan is talking about without having to tear into a bottom end potentially. I have no idea what condition the motor is really in but it does run, Dave had it on his engine test stand, and I believe he had compression numbers and what not that all looked good. Not sure if it was in a driveable car at one point to know the trans condition.
I am not anywhere near you so the shipping complicates things a bit.
Would you sell him one of your 1275's?
The thing Dan is talking about is putting a 1098 crank in a 998 to give it more stroke. It makes a quicker revving engine that makes more power than a stock 1098. It usually needs special pistons tho.....I think Russel in Australia sells the kit and is a big proponent of it.
Couple different ways to do it. Russell and maybe Calvert sell some very oversized pistons to make a 1225cc or thereabouts. Otherwise maybe there are specific height pin small bore pistons to make it work out for 0 deck height and the gasket for proper quench and piston to head clearance without machine work or specific rods. We'd have to research it a bit. All a 1098 is really is a stroked 998. The Russell pistons are just one avenue to take a small bore and basically turn it into a large bore. It would be a really nice motor.
I had found that VMAXSCART was still around and making their A-Series supercharger kit. I have been researching both as I had more/less decided after my talk with MiniDave to go with some form of "forced induction".
I am actually leaning more towrds the Turbo kit as it was designed by Jet Motors (US based, so more convenient support) who have sold a significant number of the kits and their kits are also being sold by some of the UK Mini parts suppliers.
I have spoken extensively this week with Jeremy about his kit and compatibility with my current engine specs. I am likely to order the kit later this week. I already ordered the parts to sort the drop-gear issue from Mini Spares and will in fact be changing from the current square-cut 1.04xx ratio set to the "economy" 0.958 ratio set - resulting in something closer to a 2.95 final.
He estimate what power it will make?
I have not heard from Stuart at VMAXSCART with numbers for the supercharger route. Jereemy at Jet Motors indicated I should see about double my current hp and torque figures with 8-10 lbs of boost with the turbo kit. Based on the conversations with Dave as well as Jeremy, that would mean between 80-90 for hp and 90-100 for torque (based on 39 hp and 52 lbft for a stock 998 and allowing for a bit more with my current head configuration).
Granted, those may be "optimistic" numbers. If reality is more like 60-70 hp and 70-80 lbft, then I will have the power gains to easily support the results of the gearing change.
I plan to add a boost/afr gauge for tuning.
Good idea on the AFR gauge.
I'm excited to see you do this, it will be the first turbo installation in our little group. However, I thought the point of going with the turbo was not having to pull the motor?
Cool, sounds like you have a plan. I have always been intrigued by the turbo kits and it's surely got to be the easiest route to go for what you want to do.
Dave,
To solve the gearing issue caused by the non-standard drop gears, I knew I would be pulling the motor to either change the final drive again or change the drop gears. I did not want to dig into the block itself. I decided to go with changing the drop gears and the turbo kit for the power boosts.
Following.
I will start another thread in the Maintenance/Modifications category when I get started on the project. Right now, I am collecting the necessary parts for the power upgrade and a couple other details.
Here is the start of the new thread mentioned in the "Soliciting Thoughs & Opinions" thread. Old thread from Lounge (https://www.restorationmini.com/forum/index.php?topic=3045.0)
I have started collecting the parts I think will be needed, along with a few spares.
I got in a new set of drop gears from Mini Spares - their EVO series square cut in the selections for an "economy" ratio of about 0.9 versus the 1.04xx I currently have. I also ordered a new input bearing, since I have to change the input gear. I also got a couple of clutch oil seals, housing gaskets, and manifolds gaskets. I am getting the Jet Motors Turbo kit with the complete intake, carb, fuel pump, and fuel pressure regulator. I am also getting their dual boost/AFR gauge and mounting pod. I found on ebay a vented rocker cover for the A-Series from a Morris Minor that I can refurbish to have extra venting as recommended. I am also going to upgrade my ignition coil to a "Flamethrower II". I can stay with my current distributor since I already upgraded it with an Accuspark module.
The plan is to start the project in November - after the area "car show season". While doing the performance upgrades, I will also be installing the exterior wood kit as used on some of the Mini Estates from the 1960s.
I will try to post more with pictures as the whole project progresses.
New thread in the "Maintenance and Modifications" group is here:
Turbocharging thread (https://www.restorationmini.com/forum/index.php?topic=3046.0)
I'm excited to see the turbo kit go on, post up lots of pics, please!
BTW, those straight cut drop gears are NOISY! That's why stock ones are helical...
Following. :grin:
What will you be using to create a timing map?
No ECU to map.
I will be using my existing 59D4 distributor with the Accuspark module instead of points.
Per Jeremy, the timing should be set for about 18* advance (BTDC) at 4K rpm with the vacuum advance disconnected.
I plan to obtain a new timing light with advance feature and check my current timing at that setting to compare. I currently have a non-advance timing light that I used to set the current timing at 8* BTDC at 1500rpm per the Haynes manual.
Wow, 18* is not much......stock Minis are more like 32-34* at 4K....
Yes so don't do that. Get with the times and run proper timing. His suggestion is straight out of the 80s. Spend the money on a 123BT, the blue tooth version that is programmable. I can make you a map in about 2 minutes that will give you vacuum advance, regular timing outside of boost, and vacuum retard in boost.
Here is a very quick example of a boost map I created based off my bus mapping. type 1 and A series are pretty closely curved with the exception of the vacuum signals and subsequent entry points for vacuum advance.
As a bonus you get a cool dashboard. Everything is monitored and tuned with your phone.
Also just looking at his kit, it doesn't come with an intercooler. This is another important factor you must consider. You can either drive in boost as needed, but never too long on hot days, or add a way to cool the intake charge.
Coincidentally I needed to top off my boost fluid in the rx7 just now after taking it for a spirited drive. You should either install an intercooler or adapt h20 or h20/meth (-20 is 67/33% mixture) to spray into the turbo. I can show you how this is easily done. I've since converted to oil burner nozzles and made my own adapters for my bus type 1 motor. Better atomization, great filters, and a clog free design. I'm building an NA race motor for it that will run on pump gas as a result. The rx7 gets 25psi on pump gas. Normally limited to 15psi with pump gas but the h20 makes that big of a difference. Rarely have to fill up the rx7 because it only activates at low boost.
In one of the videos about the turbo kit, Jeremy mentions using 28* on a turbo'd 998, so I thought the 18* he said when discussing the purchase seemed off. That is also why I was going to measure the current advance at 4K rpm (vacuum disconnected) for comparison.
I looked up the 123BT: $575 if ordered direct from the 123 USA division! Also, I don't have a compatible device for the software. The only Bluetooth capable device I have is my Macbook-Air running MacOS. The 123-Tune software is made for either Android or iOS (iPhones or iPads).
I plan to keep the boost on the lower side - 8 to 10 psi max. The afore mentioned video of a turbo'd 998 was also limited to 10 psi max boost.
I'd run 30-32 degrees out of boost with vacuum connected giving 40-42 at light throttle, and 22-24 degrees at 10psi. I'd get a device that works with a 123bt. But I also would run an intercooler or h20 because otherwise you are surely on your way to sadness, broken stuff, and a crappy running turbo setup with poor fuel mileage and really hot egt's. Your oil temps will also be hotter and you may need to factor in that as well. Oil cooler or synthetic at bare minimum if your temps are getting out of control for conventional. You'll know if it works or not on a hot day doing sustained hill pulls by going the easiest route possible.
Now you are just scaring me out of undertaking the project. :17:
I'm just telling you things I'd be doing so that it works as you want it to. Put it this way, spend 3k on his kit now. Or spend 3k now, and 1k-2k on the extra details later and another however much to rebuild or source another motor after it all goes sideways because you skipped the details now. Turbos create heat. A lot of it. Even small ones do. 2 inch intercooler piping and some small generic intercooler isn't going to break the bank. A $600 distributor that properly gets timing where it should be is also cheap insurance and will make a hell of a big difference in overall driving enjoyment. Locking an old dizzy at 24° in the year 2026 is ridiculous. Or just backing one out to max out at 24° will make the thing soggy and hot down low, might even backfire out the carb off idle honestly. This turbo cools via oil I'm guessing. That's something that I'd stick a gauge on and see do I need an oil cooler. Anything above about 240f on oil temps with conventional oil is getting too high. High intake air temps, boost, and high timing will create the kind of detonation nightmares are made of. This is assuming you get the fuel dialed in to 12:1 or a little richer at 10psi and below. Not trying to rain on your parade but just slapping on a turbo kit without other considerations is asking for trouble.
I did a mental double-take on the vacuum advance VS turbo boost. Then I remembered vacuum occurs when the throttle is closed (or partially) so boost wouldn't affect vacuum. At 4000 rpm, throttle is open so virtually no vacuum. And there'd be boost, right? So, at 4000 rpm having the vacuum connected or not should not matter.
I have one of the first generation 123's which does not consider vacuum at 4000 rpm. It's on a 1275cc high compression 10.5:1 and it still works flawlessly.
(I'm ready for an explanation of there I've gone wrong!)
Quote from: Dan Moffet on September 13, 2026, 01:19:16 PMI did a mental double-take on the vacuum advance VS turbo boost. Then I remembered vacuum occurs when the throttle is closed (or partially) so boost wouldn't affect vacuum. At 4000 rpm, throttle is open so virtually no vacuum. And there'd be boost, right? So, at 4000 rpm having the vacuum connected or not should not matter.
I have one of the first generation 123's which does not consider vacuum at 4000 rpm. It's on a 1275cc high compression 10.5:1 and it still works flawlessly.
(I'm ready for an explanation of there I've gone wrong!)
Yes if the vacuum is connected is would make 24° at 4k rpms at close to full throttle and 34° at light throttle with a canister that adds 10° as most do. Under boost it would be 24°. Early 123s just had 16 selectable curves and none were for turbos. The style I'm talking about allows boost retard. You get a flawless and perfect curve, can run a 60k volt 1.5 ohm coil as well. The next best thing is trigger wheel but that's a different can of worms. The 123bt is easy. I'll gladly make a map that will work fantastic and safely.
Edit again: if the dizzy is locked out then it just stays at the fixed position regardless of vacuum and throttle position. That's the old school way of doing it. You gain some mid range, but cruise like shit, and may experience kickback on startup.
The simplest thing would be to add the squirter to the intake system, once the car is up and running - if you find that you're getting detonation. But with 8.5 compression and not getting crazy on the boost and setting the timing correctly I think it will be OK.
If needed I have a brandy new 13 row oil cooler I can sell you, those are an easy bolt on deal too. (and no tarrifs! :-) )
Intercooler is a different can of worms, only because there is so little room to mount one, even a small one, and run the necessary piping.
Do you need a one way check valve in the vacuum line to the dizzy so that you don't send boost to the vacuum advance?
Pros to h20 alone without an intercooler are not having to get creative with the piping and intercooler installation. You could in theory run lower octane fuel at your boost level, especially if you use a water/meth blend. It makes it virtually detonation proof if you screw up air fuel ratios or run excessively high timing. You can tweak the air fuel ratios with it by altering the methanol volumes. It turns a small turbo into a not as small turbo by pre spraying the inlet, effectively increasing the turbine wheel mapping efficiency. Cons are you have to install a kit and remember to add distilled water to a reservoir or any blue washer fluid which contains only distilled water, methanol, and blue dye.
I have a snows performance boost controller for a turbo kit I never used. I think there's just a few additional items to add for it to sense boost on when to activate the pump. You'd have it activate at something like 3psi and ramp from low volume at 3psi to it's highest volume by 10psi, which on this power output wouldn't require a ton of volume. It doubles as a boost gauge and shows activation and when the reservoir is getting low. A standard 3qt reservoir would last awhile. It would ensure summertime long hills you're not pinging yourself to a flatbed tow home. Pro meth sells small pumps for very affordable prices that would work great on something like this. I would donate my time to machine a properly sized GPH oil burner nozzle and adaptor and afix it to any turbo filter you have.
You're thinking about this all wrong. For $0.00 you can rip out ALL OF the interior (except the drivers seat) and only run 1/2 tank of fuel, 1/2 JUG OF W/W FLUID etc.. Remove anything that weighs anything(even the headliner) Helium in the tires. Sand it down to primer - heck cut off the roof even.
BOOM, you're 500 lbs lighter.
Car runs like it has a turbo!
You're welcome. :cheesy:
Sounds like a fun project to give your Mini some more oomph.
Go for it, it will put a smile on your face when its all done.
Just remember, boost is addictive!
As Dan has mentioned above, timing is very crucial for a turbo motor to run properly and NOT self destruct itself. Old adage: More power = more heat. By keeping the heat in check, you're able to safely run more boost and your engine will be much happier and last longer.
I went through this same exercise as yourself, except I decided to build my own kit.
Even though I have on hand an old Metro turbo dizzy, I went with programmable ignition to control the timing and make sure timing is correct throughout the speed and load range.
Lots of good info on the internet, and people are willing to share their experiences of what is proven to work successfully.
phil
I did some reading on stock era turbo minis and metro turbos cars. The era turbo only produced 7psi and used as much as 28° timing. The metro turbos only hit 7psi by 6000 rpms and had some ecu system that had it at 4psi till something like 4500 rpms.
Screenshots of things to consider.
Quote from: ve9aa on September 13, 2026, 02:24:22 PMYou're thinking about this all wrong. For $0.00 you can rip out ALL OF the interior (except the drivers seat) and only run 1/2 tank of fuel, 1/2 JUG OF W/W FLUID etc.. Remove anything that weighs anything(even the headliner) Helium in the tires. Sand it down to primer - heck cut off the roof even.
BOOM, you're 500 lbs lighter.
Car runs like it has a turbo!
You're welcome. :cheesy:
Reading this makes me appreciate Dans build with Blue. Not only did he squeeze that 1275 to 96 hp he got the weight stupid low at 1100 lbs.
I have nothing to add except after owning a couple of turbo cars one heavily tuned, adding that heat to the engine bay has to be taken into consideration. Better radiator, oil cooler, inter-cooler would also be a consideration, or H20 injection. I would also consider EFI and stand alone, like a Wolf 3D or something like that just so you can tune the timing and fuel to get the most out of the Turbo.
Interested to see how this turns out.
Here is a 36 minute video that goes into detail about the design intentions of the Jet Motors turbo kit. It addresses all the concerns mentioned above.
Jet Motors Turbo Q&A video (https://www.youtube.com/watch?v=lJwR-XpawbI)
The afore mentioned 18* to 20* initial timing is the "starting point" reference with up to 24* as the preferred upper limit for 4K rpm (vacuum advance disconnected).
That degree per pound of boost is a pretty safe place to start. Which at 10psi puts you in the 22-24° range like I mentioned. They do say you can run vacuum, I think they're just saying set it to 22-24° at 4k without vacuum connected like you'd check max timing anyways. I suppose at light throttle cruise you'd at least be in the 30s this way, though that's not particularly ideal for lean afr's cruising. 32+10° is better for lean cruise. With a 123BT you can get it exactly 42° at 4k rpms at light throttle pulling vacuum, exactly 32° at 4k rpms at and near 0 lbs of boost (naturally aspirated throttle position) and exactly 24° at 10psi at 4k rpms. But better than that you'd have 28° at 5psi. It would perk up the whole powerband. That gt15 is what is what I have sitting on my shelf for the turbo kit I was putting together. I chose one with a slightly larger exhaust side at the time since the turbo itself is pretty small. Gt15 is just the series like a T4 I run on my rx7. Then you configure the details of the turbo itself. Anyways, back to h20, it would liven that turbo up yet retain the quick spool he talks about. Think gt15 response but gt17 top end at full boost. He mentioned high boost being tough on the rings. Well that heat reduction solves all that.
Yeah a water/meth setup really helps solve a lot of the issues a turbo can introduce.
Quote from: cstudep on September 14, 2026, 07:51:06 PMYeah a water/meth setup really helps solve a lot of the issues a turbo can introduce.
It's a cheap insurance against a bad tune, questionable gas, heat, and big time performance gainer when taking advantage of it. I've been doing it for a decade on my rotary engine and 2 years on a naturally aspirated type 1 motor. Both applications have far exceeded expectations. The naturally aspirated type 1 motor perhaps even more than my turbo rotary surprisingly. I've used it as only cylinder head heat reduction on my 2180cc. I can't under any circumstances overheat the engine. The 2387cc motor I'm building I'll increase the compression ratio dramatically to gain performance. Much like increasing boost by 10psi on the rx7. I've also been able to increase timing safely in both applications by a couple degrees. That's the "cool" thing about it, because if 10psi on a 998 doesn't provide hill climbing performance you want, just increase the boost till it does. In the case of the PT6266 turbo on the rx7, around 18psi would normally be the max boost before it was done making power. But with the h20 it just keeps making power far beyond that. I use a 2 phase controller, same as the spare one I'm not using that was going to be for my 1310 blue mini Jim has now. System activates at 10psi, full spray volume at 18psi, and at 19psi the pre turbo nozzle kicks in. I may revisit this on the spare 1275 that came with the pickup that needs rebuilt.
How do you like the snow system? I have been looking at adding a water/meth setup to my old 12 valve Cummins truck. I have upgraded the governor springs, fuel plate and a few other boost mods. Which obviously all increases EGT. I have a set of injectors/delivery valves but won't install until I get a little bigger turbo. For the most part they stay resonable but when I'm towing heavy up any sort of grade I have to keep an eye on it.
It's good. The snows gauge controller does everything you want and need. Looking back at what I use it's the 2.5 version kit.
Looks like they have kits specific for diesel applications too. I was looking at the stage 3 version or whatever they call it as it reads boost and egt which is supposed to be super helpful for towing applications.
They do, pro meth does too.
I hadn't heard of then before but I like the name, not just regular meth like your typical rural town drug dealer....but pro meth like they know what they are doing. Lol
In all seriousness I do like how clean their system looks with the distribution block thing, and they offer different levels of kits so you can source your own tank etc...does not look like they have a way to reference the EGT though.
Sorry for high jacking your thread MPlayle I'll try to refrain from commenting further.
It is only "sort-of" hijacked. The discussions that have been going on in this thread kind of go together with the original thread in the Lounge.
I am going to see if I can merge the two threads under to original thread in the Lounge, then I'll start a new one dedicated to just the install project (hopefully).
Staying sorta on topic of h20 and professional top grade meth... cstudep if you're spraying high volumes a standard h20 nozzle works great. Pro meth has a better selection. If it's low volumes, as is the case with a turbo mini or most naturally aspirated 4 bangers, modified oil burner nozzles are far superior in atomization and clog resistance. I've done the bench test!
I saw that you mentioned that sort of in passing further up the thread. I wouldnt be opposed to further elaboration on the topic since it would apply to our minis which I am also very interested in putting a turbo on one of these days.
I also dont yet know what kind of flow you would need in a diesel but guessing it would be somewhat high at times being that I can see boost up to around 40psi on my current setup.
I have seen claims water/meth at around 50/50 can add around 40 to 50hp since adding fuel is how diesels make power and meth is a fuel. Of course its all dependent on everything else, you can add fuel to a point but eventually you need to start adding air as well.
There are charts that show you what volume you need for the amount of horsepower. You'd use a transition style system that starts low and ramps up as you get to 40psi. On a 75hp mini You'd only need about 0.50-0.75gph flow, which is virtually nothing. I use 800cc's on my rx7 that's 500hp. The bus gets 1.2gph and made 135 to the wheels. I will up it to 2gph with the 2387 in a 2 phase approach. The oil burner nozzles atomize about 100x better at low volumes. It comes out as a fog whereas standard nozzles are large droplets in a small volume nozzle. You want the fog for pre turbo. Bench testing the webbers with a shop vac pulling through the ram pipes, the oil burner nozzles don't even need to be directly over the intakes. Just getting it anywhere close the fog gets drawn in. A standard nozzle has to be directly above.
As far as power goes, well you only gain it a few different ways. By having the ability to increase timing, raise boost, raise compression, or in the case of this 998 by reducing intake heat dramatically since no intercooler is present. You'd see some gains spraying pre turbo on your diesel. If you just toss on h20 and do nothing else you gain nothing.
What are the oil burner nozzles you use? I assume they are the same nozzles that are used in oil burning furnaces and what not, so when I do an amazon search it comes up with a bunch of brass nozzles for such things.
How are you modifying them, just how you mount them or are you actually having to do something to the nozzle itself.
On the diesels most people just drill and tap a hole in the turbo intake pipe and then thread in the nozzle as it seems most of those nozzles are threaded on the front side. The oil burner nozzles I am seeing are only threaded on the back side but I may not be looking at the right thing either.
I'll search out these charts you speak of, I have not looked at one yet. Still early in my planning phase on this.
Delavan is the brand. You can get low volume in a "clog free" design. Harder to find but I bought a bunch. I machine them so they can be threaded into a bung like a standard nozzle.
Pics and video
(http://www.restorationmini.com/forum/gallery/1-120626141552.jpeg)
(http://www.restorationmini.com/forum/gallery/1-120626141615.jpeg)
Nice, thanks for the info. Those do atomize really well. I need to finish up cleaning up my lathe so I can put it back to use.
Hollow pattern with a 90° angle is what I'm using. Seem to atomize the best. Night and day difference from a same sized standard nozzle.
I've been on vacation the last couple weeks so I'm just reading this thread now.
Quote from: MPlayle on September 13, 2026, 10:28:15 AMAlso, I don't have a compatible device for the software. The only Bluetooth capable device I have is my Macbook-Air running MacOS. The 123-Tune software is made for either Android or iOS (iPhones or iPads).
Michael, this may be the impetus you need to abandon your Bush-era flip phone and join the rest of us using smartphones. I'd be happy to help by giving you help on the learning curve and I'm sure you'll find it very easy to upgrade. A Smartphone doesn't need to be expensive you can get one on a cheap monthly plan. The Bluetooth to access a timing map is just one of the many advantages.
Another option if using modern day phones isn't of interest.
https://www.cbperformance.com/product-p/2013.htm
I just sold a used one I experimented with on my mini and bus. Does boost retard and everything in between in a 3d map format. I should even have the locked out dummy distributor for the mini still laying around in the shop you can have. Only issue was I had to convert back to points because the electronic module in the mini distributor gave horrible kickback on startup with electrical interference. Used it for several years on the bus till going 123BT for...well Bluetooth and a cleaner setup. The blackbox is old-school with a serial cable for windows 98.
Michael, this may be the impetus you need to abandon your Bush-era flip phone and join the rest of us using smartphones. I'd be happy to help by giving you help on the learning curve and I'm sure you'll find it very easy to upgrade. A Smartphone doesn't need to be expensive you can get one on a cheap monthly plan. The Bluetooth to access a timing map is just one of the many advantages.
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If you just wanted bluetooth and a browser to download the app, you could probably get a cheap smart phone (new or reconditioned) and skip the plan altogether. You'd also have the bonus of a camera and other apps.
I recommend keeping a search active on Ebay for a K100 or K1100 head, cheap from bike junkyards here. Maybe get one for less than $200. Then buy the conversion kit from Specialist Components or other twinkam providers, should double hp.