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Thread: SR20DET powered Race Car - Advice Please

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Posts: 11-20 of 23
2015-09-24 20:32:16
You've come to the right place. I see most of your questions have already been answered correctly so far. I will chime in if I see any that were missed.

FMIC = Front Mount[ed] Intercooler

100C for coolant temps is fine. 110C is where you should start to worry.
Last edited by BenFenner on 2015-09-24 at 20-34-03.
2015-09-24 21:48:09
Thanks for the replies guys, really appreciate everything.

So to me 400bhp sounds like it is marginal, I want total reliability, I would like to run some endurance one day with the car as well maybe ? 450bhp is really going to be where it is at ultimately in the future ? What parts are a must have for this power level, and can lag still be controlled to a sensible level without worry about anti lag systems and such alike ?

In the series we currently race we do 15min sessions for both qual, and races...

You mention 100c is ok on the water temp, but it only gives 10c overhead, I would prefer 95c ? anyone used that wet water stuff ?

When you mention induction piping you referring to air intake cold feed type thing Lee ? sorry complete newbie with this turbo malarky

EFR/GT/GTX turboEFR/GT/GTX turbo <<< what's this ?

Thanks again everyone, appreciated.
Last edited by Marc Reynolds on 2015-09-24 at 21-50-42.
2015-09-24 22:18:16
Endurance racing reliability and 450 HP will come from keeping temps under control. It can be done with stock internals.
If you don't absolutely trust your tune or heat exchangers, then forged pistons are in your future. Might as well go with forged rods while you're at it.

If you do pistons I would raise the compression up from 8.5:1 (what you have now) to around 9.5:1 compression (what the N/A SR20 engines got stock) to help with boost onset. You're not making so much power that you need the lower compression.
You could look into an upgraded oil pump. There may be an easy way to get the higher pressure and higher flow SR20VE oil pump/front cover installed.
If you want to get into the head to do head work you can, but minimal work will be required if any.
Get some Jim Wolf Technologies S4 HL cams in there if your rules allow it.
That should do it for a reliable engine assuming a reliable tune and great cooling.

You can get 450 HP from a 3rd generation Garrett turbo (GT3076 sized) very easily if you pay attention to the details. Delayed boost onset (which is what you're actually talking about, turbo lag is not the same) with this size of turbo is relatively minimal on the street, and almost non-existant at race RPM. So I wouldn't worry about that. Go for the 4th generation Garrett turbos (GTX series) and you will eliminate any worry of delayed boost onset.
Take care to get your Blow-Off Valve setup done right, and recirculated, and you should avoid common boost onset delays during shifts too.

Water Wetter has been tested and recommended by those racing SR20s in the past. It should be a safe bet for a bit of margin.
For a 1990s engine, the SR20 runs "normal" water temps. However, cars these days run MUCH hotter water temps. While our fans come on at 97C (really?) most engines these days aren't even getting into their stride until they are in the 102-105C area. The idea is fuel economy, but for a race car it can also mean power. Getting that fuel to atomize better with hot head temps works. Personally, I'd be happier with 100C temps than 95C. Just realize that 110C is getting warm, and 115C is time to shut it down.
Your radiator looks more than up to the task, so it will be down to ducting. Also, consider getting rid of all 3 of your fans, or keep maybe 1 if you must. The fans do absolutely nothing above ~30MPH and only hurt you above that speed.

EFR = Current turbocharger generation made by BorgWarner, comparable to the 4th-gen Garrett GTX turbos.
GTX = 4th-Gen (current) Garrett turbochargers.
GT = 3rd-gen Garrett turbochargers.
Last edited by BenFenner on 2015-09-27 at 20-02-08.
2015-09-24 22:24:04
Originally Posted by BenFenner

GTX - 4th-Gen Farrett turbochargers.

You might not make your HP goals, if you go with this setup.
2015-09-24 23:40:33
Brilliant useful info thanks

Some stuff to chew on initially then, we had already been looking at whether we should find a strong oil pump etc as we plan to fit slicks to the car next season along with baffled larger capacity sump etc, (its running smaller than std atm)

How about spark plugs ? any recommendations ?

Oils ?

Sorry for all the questions, we really are starting from the start with this engine here, ask me about a BMW engine and I know my stuff, this is all alien to me tho
2015-09-25 00:05:51
- Larger, baffled sump is always a way to go ESPECIALLY with slicks. Look into an accusump atleast when going to 100 TW or anything more sticky (more so that you have aero work done. I see a minor splitter/M3 chin spoiler).

- Spark plugs are simple. BKR7IEX (or whatever). Done.

- Oil - Rotella T6, but there is a multitude of better oils out there at this point. T6 is a good start however.

The SR20 is hilariously simple and robust engine. It really doesn't take much to make them bomb proof, tractable and powerful. Anywhere from a 300WHP to a 1200HP have been done with great success, so you really don't have to look far with these things. Aftermarket is compatible to BMW engine wise. If you can think it, it has been done.
2015-09-25 01:31:51
For now a double platinum or platinum/iridium NGK spark plug in the heat range of 7 as mentioned above is the perfect mix of quality, performance, and value.
You'll want to go to heat range 8 once you start making that real power.

(There are better plugs, but not worth it IMO.)

I like Amsoil for oil, but if you stay on top of it anything synthetic will be good.
Last edited by BenFenner on 2015-09-25 at 01-39-08.
2015-09-25 01:34:40
Ps my apologies for constantly mixing units while posting.
2015-09-25 09:39:46
Originally Posted by Boostlee
Ps my apologies for constantly mixing units while posting.

That is completely fine lol, being a Brit I am completely used to it, we mix stuff all the time

Any thoughts on grades of oil ? 5w/30 maybe ? previous owner was using 10w/40 semi synthetic ?

Are these engines sensitive to coolant type and head gasket failure due to wrong coolant ? one of the biggest causes of head gasket failure on BMW engines is the wrong type of coolant.

Thanks chaps
2015-09-25 12:41:35
While I will argue that BMWs aren't sensitive to types of coolant (don't buy the hype*), the SR20 is going to be absolutely fine with whatever you put in it. 99.999% of us use the good old green stuff. (Or pure water if actually racing.)
Just don't use anything with some stop-leak bullshit pre-mixed in. I know some American cars call for this stuff to combat their horribly porous aluminum castings.

All else being equal, oil weights should be heavier than recommended by Nissan if you're tracking this thing. The thinner oils are for fuel economy, and suffer in protection. 10w40 is a good weight to start with.

*It's actually down to how full the reservoir is. The air column in the BMW reservoir is a spring which dictates the pressure of the system. Half full is the correct amount. Less full and the system will try to hold a lower pressure and you'll get premature boiling, more full and the pressure of the system rises often to the point of blowing out whatever the weakest link is.
Keep the reservoir half full as recommended and you won't see any of the problems people complain about (except failing plastic water pump impellers, those are a given). The thermostat housing won't fail, the reservoir won't fail, you won't overheat, you won't have headgasket issues, etc.
Last edited by BenFenner on 2015-09-25 at 13-11-21.
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