M90 Race Car Engine Build (Now with more M54!)

[nik77356]

Well, for $500 just for a set of rings, I'd rather just go ahead and double that, and get a whole new set of custom pistons.

[BuzzBomb]

As someone with actual experience with your situation, as I stated in the other thread, the restrictors are there to slow the flow of oil into the head, not starve it. All race engines I build, whether M10 or M30 get restrictors. Period. Never damaged valve train from oil starvation. Also, M10/30 engines used in competition typically don't use the OEM valve cover to intake EGR hose, it's catch-can time. As far as the "B35" oil pump is concerned, the driven shaft is the same as all M30 oil pumps that have a single center held gear. The difference is diameter of the chain gear and the chain length. Late B34 and B35 blocks that use a tensioner have a smaller gear and longer chain. M30 based blocks before '87 share the same length chain and gear size, so just use the earlier hardware on whatever pump you use, along with the B35 pickup and pan. Another thing you can do is with the head totally disassembled, you can open up the drainage passages in the head and "port match" the gasket to the drain holes if necessary to help oil exit more efficiently. I would not suggest making any changes to the block itself, though.

[BuzzBomb]

Well, for $500 just for a set of rings, I'd rather just go ahead and double that, and get a whole new set of custom pistons.

The last M90 set I got were from Deves. A couple hundred for the set. Call them on the phone for faster service. I had mine in less than a week.

[BuzzBomb]

Wallothnesch has everything for the M90 including piston rings and head gaskets.

https://www.wallothnesch.com/en/motorte ... 11-29.html

Unfortunately, unless you wanted to spend some money on a "Cometic" style gasket, which you can order in whatever bore size you want, W&N is one of the few places that an M90 head gasket can be found. Just buy the head gasket though, not the whole kit. The rest of the engine gaskets they offer are pretty poor quality from what I've experienced.

[nik77356]

Well, for $500 just for a set of rings, I'd rather just go ahead and double that, and get a whole new set of custom pistons.

The last M90 set I got were from Deves. A couple hundred for the set. Call them on the phone for faster service. I had mine in less than a week.

Holy shit, this is the answer! I talked to them, and they'll have a set made for me by the end of the week, if not sooner! You rock!

On the Head Gasket, Levent at GutenParts is sourcing one for me.

[WVe28]

M30 based blocks before '87 share the same length chain and gear size, so just use the earlier hardware on whatever pump you use, along with the B35 pickup and pan.

I did exactly this with a B35 pump and pan on my M90 block. Seems to be functioning appropriately.

W&N is one of the few places that an M90 head gasket can be found. Just buy the head gasket though, not the whole kit.

Yup. I had a helluva time finding the M90 gasket until I found out about W&N. I ordered the gasket from them and had it within a week. My bore is 94mm and it fit fine. That was my only concern, initially. The gasket is 1mm overbore (so 94.4). I ended up getting a full top end gasket kit for a B34 and bottom end for a B28/B30 from FCP just because I was too lazy to source everything individually.

[VintageRacer]

I applaud this thread for highlighting that you can be frugal in building a hi performance engine for track driving. However for those on the sidelines reading please don’t confuse this with what it takes to build a full competitive engine like the old Group A M30’s. Custom pistons were a minor expense and may be false economy in the long run. But like any engine build it’s all about the end goal and the funds available. For me custom pistons meant I could go to the S38 144mm rods and allow any compression ratio and chamber profile to improve quench. Granted I trusted my engine builder who is one of the top M10 race engine builders in the US. I think this also highlights how experience is worth the money. I’ve built plenty of VW air cooled motors and Datsun engines but at no point do I think that qualifies me to build a racing M30.

I haven’t run my engine yet but I’ll post up when she’s installed and on the dyno. It won’t be what our 4.0L S38 makes but it will be historic and I will rev the piss out of it because it costs 1/3 of the S38!!

[nik77356]

A bit of an update, I was able to source the Piston Rings very easily once I knew where to get them. Thanks for the source, BuzzBomb! Levent is working on getting the Head Gasket, but apparently his supplier is giving him some troubles with getting it. The Bottom End is done, the Cylinder Head has been slightly delayed, as the machinist's wife has gone into the hospital. Hopefully she gets better soon, for their sake, and also my Cylinder Head's sake.

In the meantime, to try to not miss another race, I put the old B34 back in the car, and converted it to M1.3. In this process, I now have a pretty large stumble off idle under zero load that I did not have before. The only changes I have made are converting it to M1.3, and adding a super lightweight flywheel (8.5lbs). I have not yet checked for vacuum leaks (haven't been able to snag the smoke machine from work yet), but if I unplug the TPS while it is idling, and then rev the engine, the response is totally normal, and then the engine will idle high, but also still respond fine to throttle inputs. With everything plugged in and the engine running under no load, it will respond fine to slow throttle. We'll see what I can dig up, hopefully this weekend.

In the meantime, since I couldn't get the car running for the race last weekend, I borrowed my good friend's SpecE46, which very easily slots into ST5, the class I run. Here is a video of Saturday's race: https://youtu.be/_FQixB-X8SU

[athayer187]

I had a similar issue when I swapped M1.3 years ago. The issue was my TPS. There should be two times it switches - just off idle, and WOT. I can't find the pinout quickly here at work, but I'd just get a new TPS and be done with it. FWIW - the spare I had on the shelf didn't switch at WOT, so I ended up buying new.

[nik77356]

I had a similar issue when I swapped M1.3 years ago. The issue was my TPS. There should be two times it switches - just off idle, and WOT. I can't find the pinout quickly here at work, but I'd just get a new TPS and be done with it. FWIW - the spare I had on the shelf didn't switch at WOT, so I ended up buying new.

That was one of my few things to try. Although, everything worked fine when it was on M1.0 with the same TPS, and then I swapped over another known good TPS (allegedly, it appeared to be operating properly when that car last ran), from the car the M1.3 Engine Harness came out of, but I will order a new one and see.

[athayer187]

I had a similar issue when I swapped M1.3 years ago. The issue was my TPS. There should be two times it switches - just off idle, and WOT. I can't find the pinout quickly here at work, but I'd just get a new TPS and be done with it. FWIW - the spare I had on the shelf didn't switch at WOT, so I ended up buying new.

That was one of my few things to try. Although, everything worked fine when it was on M1.0 with the same TPS, and then I swapped over another known good TPS (allegedly, it appeared to be operating properly when that car last ran), from the car the M1.3 Engine Harness came out of, but I will order a new one and see.

Listen for "click" and probe pins with a volt meter. Something should change just off idle (some combination of pins will open or close continuity, I honestly don't remember!), and something should change at WOT.

[nik77356]

I finally got the engine block back from the machine shop!

[LeiseyJr]

Looking good!

[djjerme]

I'll pull the valve cover off my race motor this afternoon and get a pic of how we modified it to fix the smoke issue. My buddy has done the mod on a few race M30's and it cures the issue; at least after hours of racing I haven't seen any smoke like it did before the mod...

[nik77356]

I'll pull the valve cover off my race motor this afternoon and get a pic of how we modified it to fix the smoke issue. My buddy has done the mod on a few race M30's and it cures the issue; at least after hours of racing I haven't seen any smoke like it did before the mod...

That would be fantastic! Thank you!

[tschultz]

Curious to see the details of this^^

[djjerme]

Here y'all go.

It's pretty simple - just silicone on the edge and then two small bends on the sides to allow the accumulated oil to drain in a better direction. Again, this was done on my own car, and the team Chumpcar - which it lasted through a 36 hour race in Spokane, along with all the other races until the car got destroyed. I'll admit, not the prettiest solution - but racing is not always about looking good, it's about finishing.

[LeiseyJr]

Here y'all go.

It's pretty simple - just silicone on the edge and then two small bends on the sides to allow the accumulated oil to drain in a better direction. Again, this was done on my own car, and the team Chumpcar - which it lasted through a 36 hour race in Spokane, along with all the other races until the car got destroyed. I'll admit, not the prettiest solution - but racing is not always about looking good, it's about finishing.

I love you. I will be doing this.

[adam_poll]

Does the silicone fully seal off that side or just the edge? I'll also be trying this to avoid possible future black flags for clouds of blue smoke

Thanks, Adam

[BuzzBomb]

Or you could just put restrictors in the block's oil passages to the head to reduce pooling, which is the primary cause of what you're trying to fix.

[tig]

Don't forget to torque the crank nut correctly.

[nik77356]

Finally got the Cylinder Head back a few weeks ago. Now to find the time to assemble it all!

[tschultz]

Looks great. But is that corrosion on your mating face? Glad it isn't going to be boosted...

Should be a sweet build! I'd think you could make similar power to an S50 or S52 depending on how well the head and cam allow the engine to breathe. Depending on your final compression, you should be able to make more power than B35 and have over 220hp. The real nice part is that you will probably have more torque at ~3000rpm.

I'll throw this tidbit out there, I finally drove my euro '81 635 (M90) with the Motronic intake manifold (B32/B34) and noticed that it doesn't have the same top end as the individual runners of my Ljet car. It seems to me the Motronic intake is biased towards low end torque and not top end power. Supposedly these two should have the same cam, although with different distributor drives.

I guess it could be the difference of the ECU timing vs distributor advance curve, but it felt to me more like soemthing with the two intake manifolds-- power drop off felt like My US spec M30B34's.

'80


'81 running M1.3

[nik77356]

Well, a LONG overdue update.

I got the engine assembled and installed in the race car, and raced it this past weekend. HOLY crap what a difference! I cannot wait to be able to get this car on the dyno and see what it makes.






During the off-season, I will be taking the Oil Restrictors out of the Engine Block, as I feel they are actually under oiling the Cylinder Head at idle and lower RPM. The Valvetrain is VERY noisy, despite having done valve adjustments several times to verify and confirm that tolerances are correctly set.

I am also still having Oil starvation issues in long left hand corners, even though I am using a deeper B35 Oil Pump and Pan. I also overfilled the sump by a little over a liter, and it made no difference. I am not convinced some of the Crank Scrapers that are available will fix this issue, so it looks like I will have to have a custom Oil Pan Baffle fabricated.

During the race on Sunday, the car overheated. After getting back to the paddock, I found the Water Pump Belt had managed to flip itself over 180 degrees. After further inspection, I found the Alternator seems to be out of Alignment. It is not loose though, so I'm not sure exactly why that is yet. I'll do some digging and figure that out. It's a later Alternator, so no Bushings involved.

[BuzzBomb]

Before you take the restrictors out, put the right oil filter head/housing on. That's part of your problem right there. That B35 housing won't work correctly on an early block. They only work on later blocks with the bifurcated casting that has the drain to the sump, not the closed casting.

[nik77356]

I understand and am aware of that, but I do have the Miller Adapter installed, that is made for that exact issue.

https://www.millerperformancecars.com/s ... ter-detail

[BuzzBomb]

Regardless, consider putting the correct oil head on and see if it helps with your issue at all, just to rule out the possibility. It's a lot easier than pulling the head.

[nik77356]

Regardless, consider putting the correct oil head on and see if it helps with your issue at all, just to rule out the possibility. It's a lot easier than pulling the head.

It won't, as I have previously had this same issue with the B34 Filter Housing installed on the engine.

I'm also not pulling the head to fix the oil starvation issue on the bottom end, I'm pulling the head to fix what I feel is oil starvation to the cylinder head at lower RPM due to the oil restrictors. Two separate concerns.

[adam_poll]

What did you end up doing for your oil starvation issues on the car? Did you pull the restrictors for the oil to the head? Add in an accusump?

Just hoping for an update as there is a lot of good information in the thread. Thanks

[nik77356]

I swapped an M54 into the car. Ultimately, there is no fix for the oil starvation issues except for having a custom Oil Pan Baffle or Oil Pan made, or using the VAC Dry Sump setup. There are just so few people racing these engines and trying to pull 1.0-1.5 lateral Gs, that there is next to zero aftermarket support for M30 based engines. I went through 4 engines in 4 weekends, spinning rod bearings in each one, even with tiny oil restrictors in the block to try to keep oil in the pan. An Accusump might remedy the issues, but at the cost of added complexity. I plan on eventually endurance racing this car, so that is an added failure point I was not willing to risk introducing to the car.