M52 Turbo Feedback - Autocross Application

[PrinceE30]

I'm contemplating a Street Modified build for my 328is. I'm looking to stick with the stock bottom end for now. Due to a recent engine overheat, everything on the top end would be replaced. The bottom seems fine and I'd like the first step to be one that doesn't require removing the engine (as I continue the build, we'll go there when we have to). For reference, I have very little FI knowledge, so the intracacies of the various parts are not part of my common vernacular, yet

My goal is ~400hp to the rear wheels. The torque curve should be fat. Most driving will be between 3000 and 6500 rpms. I'll be using stock gearing (2.93) and will probably bump the redline to 7400. I need a very responsive engine (due to the autocross application) with quick spool and early torque (I expect peak to be between 2500 and 3000 rpms). Street Modified has a weight calculator for my displcaement + forced induction, so for now, the 2.8 should work and should be more than enough (current National Champion in the class is a 2.4L Nissan 240 with a turbo K24).

Likely, I'll be replacing my current head with one that has S52 cams (though if there is a better set for turbo application, please let me know) and going with APR studs. I prefer to keep the stock compression ratio as the car will be running on either E85 or race gas (no pre-detonation concerns due to compression).

I have some questions...

1. I like the idea of going with the CES manifold. From what I've read, twin scroll is a good concept. Is there any reason I should use the SPA unit instead? Weight is a concern to me and building a bottom mount setup seems like it will keep things simple (I've heard of the space constraints and I have the ability to do some a bit of massaging to make things work).

2. The lightweight nature of the BW EFR turbos seems like a perfect match. I know at least 2 current top flite SM autocross builds which have recomended them and it seems to be working out well. With my need for the early spool and and response, they seem like a perfect choice. I've spoken with a few people and done a little research and my initial choice would be a 7163. Better turbo options? Am I around the right size?

3. Internal or external wastegate? I have zero knowledge of the pros and cons of each.

4. FMIC recomendation?

5. Clutch and flywheel recomendation? I'd like to go with the lightest flywheel possible, but obviously be reliable. With the power constraints above, where do I start?

What else am I missing? Once I get the big parts figured out, I'll start fleshing out things like BOV, oiling, engine mounts, fueling, etc.

THANKS!!!

[brokeneck]

I'm doing a pretty similar build myself. I went with a 27x7x2.5 front intercooler because I figured I wouldn't need too big for lower boost levels and it fits perfectly up in the bumper with minimal cutting of the bumper, but most people will probably say go a little bigger. Although maybe go taller and not wider, length wise it is pretty close.
Turbo wise I think the BW EFR turbos are a good choice, iread about them after I bought my turbo so I kinda got stuck with my GT3076R with a .63 AR turbine housing which will spool fast but is probably going to top out kinda bad.
Even with my small turbo I think I'm going to have to do some bell housing grinding because the v band outlet is right next to it.
Clutch and flywheel I did an eBay F1 clutch kit but that's because I'm cheap.
I personally went external wastegate for when I want more power it should be better but I don't think at low boost it's super important but definitely easier if you already have it all plumbed then having to go back later. I think they are mostly just more responsive than internal ones.

What are you considering for tuning?

[PrinceE30]

TRM is 5 minutes from my house and Mike is a friend. He had done the original tuning and exhaust on my car.

[brokeneck]

Damn, I wish I was you haha

[328iFun]

PrinceE30;29846911]I'm contemplating a Street Modified build for my 328is. I'm looking to stick with the stock bottom end for now. Due to a recent engine overheat, everything on the top end would be replaced. The bottom seems fine and I'd like the first step to be one that doesn't require removing the engine (as I continue the build, we'll go there when we have to). For reference, I have very little FI knowledge, so the intracacies of the various parts are not part of my common vernacular, yet

My goal is ~400hp to the rear wheels. The torque curve should be fat. Most driving will be between 3000 and 6500 rpms. I'll be using stock gearing (2.93) and will probably bump the redline to 7400. I need a very responsive engine (due to the autocross application) with quick spool and early torque (I expect peak to be between 2500 and 3000 rpms). Street Modified has a weight calculator for my displcaement + forced induction, so for now, the 2.8 should work and should be more than enough (current National Champion in the class is a 2.4L Nissan 240 with a turbo K24)
400 is very doable on a 328. But it all depends on your Tuner. I recommend Zack with 22rpd. You wont get much redlining to 7400 on a 2.8 unless you have some expensive very aggressive aftermarket cams. I have s52 cams on my m52 and the power band is about done around 6.5 to 7l anything more isn't worth the wear/to power ratio in my opinion

Likely, I'll be replacing my current head with one that has S52 cams (though if there is a better set for turbo application, please let me know) and going with APR studs. I prefer to keep the stock compression ratio as the car will be running on either E85 or race gas (no pre-detonation concerns due to compression)FT.
FYI: You don't have to replace the entire head for S52 cams. You just need the cams.... You will pay for them if you buy s52 cams alone. You could buy an M3 Parts car for $500 more if you wait for one to pop up. m3 cams =$300-4/450, and sometimes $500. Busted M3 Car $1000.00

I have some questions...

1. I like the idea of going with the CES manifold. From what I've read, twin scroll is a good concept. Is there any reason I should use the SPA unit instead? Weight is a concern to me and building a bottom mount setup seems like it will keep things simple (I've heard of the space constraints and I have the ability to do some a bit of massaging to make things work). SPA Cheaper, only benefit. If you can go twin scroll. There's really not much "massaging" to the manifold SPA fits well. I'd imaging one twice the price would fit even better. If do go CES. Get with Butters, hes a member here and can help you out.

2. The lightweight nature of the BW EFR turbos seems like a perfect match. I know at least 2 current top flite SM autocross builds which have recomended them and it seems to be working out well. With my need for the early spool and and response, they seem like a perfect choice. I've spoken with a few people and done a little research and my initial choic
e would be a 7163. Better turbo options? Am I around the right size?
Most guys on stock bottom end go with a GT35R or GTX35R or equiv.

3. Internal or external wastegate? I have zero knowledge of the pros and cons of each.
You can change boost levels easily with an external wastegate.
Say you want to run 7PSI on street for longevity of engine and want to run 14PSI on the track, external waste gates give you better options to do so via a boost controller


4. FMIC recomendation?

5. Clutch and flywheel recomendation? I'd like to go with the lightest flywheel possible, but obviously be reliable. With the power constraints above, where do I start?
Go with chromoly flywheel and stage 3 6 puck clutch. Gripforce and F1 sell them, ebay and amazon.


What else am I missing? Once I get the big parts figured out, I'll start fleshing out things like BOV, oiling, engine mounts, fueling, etc.

Get rally road engine mount for turbo and poly or replacement OEM engine mount for pass side.

Fueling:Find a tuner first and they will walk you through all of that


THANKS!!!

[jakermac]

400 is very doable on a 328. But it all depends on your Tuner. I recommend Zack with 22rpd. You wont get much redlining to 7400 on a 2.8 unless you have some expensive very aggressive aftermarket cams. I have s52 cams on my m52 and the power band is about done around 6.5 to 7l anything more isn't worth the wear/to power ratio in my opinion

Autocross is not about making power above 6,500, but about being able to carry 2nd gear AS LONG AS POSSIBLE. If you can avoid a shift to 3rd when you're 100yards from the next corner without riding the rev limiter, you do so. Generally cars a geared to reach 72-73mph in 2nd gear on the limiter. 95% of the time, the corner comes up before the limiter but if it doesn't you don't want to shift to 3rd. 9 times out of 10, the shift (and subsequent shift back to 2nd) will lose you time over riding the limiter for 100'.

[PrinceE30]

400 is very doable on a 328. But it all depends on your Tuner. I recommend Zack with 22rpd. You wont get much redlining to 7400 on a 2.8 unless you have some expensive very aggressive aftermarket cams. I have s52 cams on my m52 and the power band is about done around 6.5 to 7l anything more isn't worth the wear/to power ratio in my opinion

The redline is more for the rare cases where an autocross strait or finish would push me past 70mph. No shifting or ramming the limiter jakermac hit the nail on the head!

FYI: You don't have to replace the entire head for S52 cams. You just need the cams.... You will pay for them if you buy s52 cams alone. You could buy an M3 Parts car for $500 more if you wait for one to pop up. m3 cams =$300-4/450, and sometimes $500. Busted M3 Car $1000.00

I'm pretty sure between TRM and OTP being up by me, there will be 1-2 parts cars I can snag the appropriate parts. My concern was if Schricks would be better or would that be a step too far for what I'm trying to attain. Thanks for the feedback on this. That'll keep the cost down some.

SPA Cheaper, only benefit. If you can go twin scroll. There's really not much "massaging" to the manifold SPA fits well. I'd imaging one twice the price would fit even better. If do go CES. Get with Butters, hes a member here and can help you out.

It was more about massaging the chassis to make the turbo fit. I've been reading up and seen Butters. Will do. Thanks for the heads up!

You can change boost levels easily with an external wastegate. Say you want to run 7PSI on street for longevity of engine and want to run 14PSI on the track, external waste gates give you better options to do so via a boost controller

I've heard there were issues with the internal wastegates on BMW applications. The boost controller things clears it up. Awesome. Anyone have any recomendations on a type?

I already have poly everywhere, so keeping things in place shouldn't be an issue. The move to solid on the suspension will be fun, though

A few more quick questions...

1. Worth going with the cutring gasket or just stick with a nice MLS + the APR studs?

2. M50 or M52 intake manifold? Or does it matter?

3. Starting with a engine that has a (probably) warped head, is there any concern with the condition of the block (ie. the deck should be resurfaced or the block should be replaced)? I will obviously know more when I get the head off, but in the mean time, wondering if I should be worried about the bottom end.