Engine and turbo build brainstorming

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Engine and turbo build brainstorming

Postby BMW BUM » Sat Mar 07, 2009 3:23 am

Okay so, I have several spare m20b25 and m20b27 long blocks to play with, so I could boost either of those or make a hybrid stroker (which is likely what I'll do since I have the parts) and no turbo parts as of yet. The car was going to go on megasquirt but I got to tight on money last semester with college and the new place etc etc.

Not planning on anything super soon exactly, but playing it by ear. Anyone think I shouldn't go ahead and boost a 2.7i hybrid stroker? Pretty sure of the 3 (or 4 if you count a lower compression 2.7i stroker but I am planning on staying with the higher compression setup) that the stroker is going to make the most power... it has the advantages of both engines, more low end torque off idle and under boost, the much better flowing head for the m20b25, the larger cylinders to cram more air into of the m20b27...

after we brainstorm that topic: turbo setup. I hate lag, it isn't even an option for this build. I want full boost under 3krpm up to redline :p I'm not wanting a dyno queen, just a shockingly quick e30 that will destroy unsuspecting victims and turn my rear tires into pools of molten rubber as I fly sideways. If I weren't such a cheap ass, I would buy a new Garrett GT28RS (aka disco potato) and rock it since spool would be pretty literally instantaneous... but I'm a cheap ass so odds are with my low initial power goals (not putting pressure over 1 bar at the most this time around) I will just find a nice holset HX35 with a 12cm^2 housing to keep spool early, and still have room to grow... all i want initially is to land somewhere between 280 and 350rwhp... maybe more depending on what all I chose for the setup and what boost I do end up running on...

Thoughts, ideas, suggestions? I intend to run MS2 for full fuel and spark, wasted spark... I am a cheap whore and will probably end up using a crappy cheapo ebay manifold, piping and fmic... the block I do end up using will be o-ringed and i will be using a stock head gasket in conjunction with this. The coolant passages will be welded, and I will run ARP head studs. Should I plan on ARP rod bolts as well? and also what bearings if any other than stock are you running?
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Re: Engine and turbo build brainstorming

Postby Yoshi » Sat Mar 07, 2009 3:37 am

I think 15psi before 3k rpms is kind of unreasonable. you will have unnoticable lag with 15psi on an HX35 and will have full boost around 3.5k.

I suggest the low comp 2.7i setup. Maybe the high comp if its 10:1 or blow CR.

Cheap is fine. 15psi should get you 350whp. i doubt youll notice the lag.

The problem with less lag systems is that they take smaller turbos. You spool quick, but you putter out up top and your EGTs go up. Ask me how I know, thats how i lost my M20.

Otherwise, your plan sounds pretty classic.
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Re: Engine and turbo build brainstorming

Postby BMW BUM » Sat Mar 07, 2009 4:14 am

I don't expect to see 15psi before 3k rpm... well unless i did drop the 1k for a new disco potato... sick spool times....

anwyas, I said a max of 1bar is what I would run, likely be running 9-11psi at first and expecting full boost around 3krpm mark is what I meant by under 3k rpm... but yeah the higher compression hybrid stroker is still only 8.8:1 or something, won't be an issue and will be much stronger than the 7.8 or whatever low comp version... we'll see what I end up wanting.I just know from others who have build boosted hybrids that the low comp version is very undesirable and weak and either a higher comp 2.7i hybrid stroker or stock m20b25 is better and makes more power.

also if i want spool earlier, i really could probably afford to drop down to 9cm^2 housing if I want my boost a couple hundred rpm lower and still easilly reach a power that will make me happy on low boost. I just want HOLY SHIT lightening quick spool, part of my requirements if I go turbo since I don't want turbo power delivery I wanted N/A power but I can no longer justify dropping $5,000 into an N/A m20 stroker with ITB's and still only having 250 max at the crank and having it be rediculously high strung with a 312* cam etc etc etc and losing all streetability at that point.

So what are your opinions on turbochargers Yoshi? I only need something to sustain a max of 450hp, if I decide I want to go over 380hp or so I will be changing much of my setup anyways, including turbo's. Basically i want stupid quick spool around 300hp to the rear wheels, plus or minus some power.
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Re: Engine and turbo build brainstorming

Postby Yoshi » Sat Mar 07, 2009 2:09 pm

10psi on a 12cm^2 HX35 actually sounds like what you want. 10psi will get you 300+whp (I helped tune a car with this exact setup).

I think you want to read more into things like compressor maps though. The "punch" you say you are looking for you ideally won't find (ever) in a turbo car. turbo chargers generally place their power somewhere in their band of efficiency. If your case, you want it down low. The problem with that is, you putter out up high. Fortunately, the HX35s compressor map is smack dab in the middle of the M20s range. The extra .2 liters should place spool a few hundred rpms quicker to boot.

I'm not so sure of your motives. You seem to want to go the NA way and want to build an NA like turbo car. That kinda doesn't work. How many turbo cars have you driven? Any Turbo M20s per chance? I think youll be surprised at how little lag most cars really have until you get to drag cars.
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Re: Engine and turbo build brainstorming

Postby jmc1590 » Sat Mar 07, 2009 3:14 pm

I also done a considerable amount of research on Fi for a 2.7 hybrid. (But no real world experience... yet!)

The following link: http://www.squirrelpf.com/turbocalc/index.php offers a great tool to compare different turbos to your need via compressor maps. Take a look. I found it very informative.
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Re: Engine and turbo build brainstorming

Postby BMW BUM » Sat Mar 07, 2009 10:00 pm

Yeah I was expecting to be able to make my 300whp without hitting 1bar. I'm not building the motor like an n/a really, just not a super low compression weak motor for boost since I'm not running much boost really. Ideally I only want to push 7-9psi to keep reliability at a maximum :D

I'm really not worried about lag at all, was just mentioning it in conjunction with my desire for a low boost relatively low powered turbo build, and to express why i would be choosing a 12cm^2 housing or 9cm^2 housing. Most prefer to run the 16cm^2 housing from what I've seen, I was simply citing my reasoning for choosing to go with a smaller housing.
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Re: Engine and turbo build brainstorming

Postby M20_fever » Sat Mar 07, 2009 10:42 pm

I am running stock 'i' CR (8.8:1) and plan to boost 25-30psi. Once I get some tires for my new wheels I can start saving for my MS setup.
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Re: Engine and turbo build brainstorming

Postby BMW BUM » Sun Mar 08, 2009 12:25 am

25-30psi lolololol... how much power are you aiming for at the rear wheels?
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Re: Engine and turbo build brainstorming

Postby joecrotch » Tue Mar 10, 2009 8:20 am

this is the exact set up I am working on right now. and should be done with in about 2-3 weeks my head is being rebuilt right now so when i get it together i will be glad to give u some feed back.
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Re: Engine and turbo build brainstorming

Postby BMW BUM » Wed Mar 11, 2009 2:15 am

sweet that would be incredibly nice to have feedback.
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Re: Engine and turbo build brainstorming

Postby DonkeyPunch » Sat Mar 14, 2009 2:52 am

Hello.
The hx35 is a nice turbo for you.
It might make 450hp like you planned. Anything smaller and
450hp is a dream. :)

It's all in tuning and revs.
Um... Full boost by 2nd gear (25psi) w/ a 16cm housing.

Dynoed the car with the same engine you're talking about,
and made 370tq at 18psi untuned. Later tuned and
added about 5 degrees at peak torque and 9 after (no dyno for that though).


Upped the boost
to 23-25 and was very quick. All on a stock engine.
"off boost" you'll make at least 50hp over stock so don't
even sweat the "lag" it's actually a good spooling turbo.

You're cruising in 5th gear don't expect to make 20psi when you floor it.
Just drop to the correct gear and you'll have your boost.

You'll probably need meth injection or race gas to reach that power.
Hope that helps and good luck.
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Re: Engine and turbo build brainstorming

Postby BMW BUM » Sat Mar 14, 2009 4:18 am

reading pwns you donk... don't recall any talk of 450hp, I was talking 280-350 range, anyways, small update, I pulled the trigger on boosting my e30, initial setup will be shitty turbo ecu piggy back setup for a max 15psi (although I'm not expecting to push over 12psi on initial setup with only 24# injectors), everyone please keep your eyes peeled for a nice hx35 for me since that and the intercooler will be the only things I have left to shop around for, everything else is already decided.

Don't expect to see dyno plots or videos anytime soon, I am acquiring all of the parts, test fitting on motor, machining block/head and putting it all back together, with sweet o-ring goodness and welded coolant passages, and a fresh oem head gasket and some ARP head studs and rod bolts.

just let me know if you spot any good used hx35's, or manifolds I might want.
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Re: Engine and turbo build brainstorming

Postby DonkeyPunch » Sat Mar 14, 2009 4:37 am

BMW BUM wrote:I only need something to sustain a max of 450hp, if I decide I want to go over 380hp or so I will be changing much of my setup anyways, including turbo's. Basically i want stupid quick spool around 300hp to the rear wheels, plus or minus some power.

:|
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Re: Engine and turbo build brainstorming

Postby BMW BUM » Sat Mar 14, 2009 4:48 am

and if you'll read the rest of the quoted sentence... like I said, I won't be going for massive power on the initial setup and if I do, I'll be changing essentially everything. Good info none the less, just razzing you a bit.
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Re: Engine and turbo build brainstorming

Postby joecrotch » Wed Mar 18, 2009 9:43 am

I was just thinking since you have so many spare m20b25's laying around *ehem maybe you could pass a b25 head this way. I will give it a wonderful home!
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