The phase 2 for the rx8 has always been utilizing a rotary muffler.
I wanna do it cheap and maybe even within challenge budget.
There isn't much info out there for turbos for gms 3.9l engine. It is a BIG v6, with not alot of specific output. 250 hp 250 tq.
I'd like to shoot for 400 hp. Redline is 6300 rpm. I'd like the boost to come in fairly early if possible. I can do the exhaust and intake mods myself. The ecu tuning will be done by sinister performance. I imagine I'll need new injectors and a fuel pump as well.
What super cheap / ebay turbo should I be looking at? What would be the ideal size for a 3.9 l v6 trying for around 400 hp? 350 would be acceptable if it means it "comes on" quicker.
Any help is greatly appreciated.
I think I would be shopping for takeoffs from an ATS-V, 3.6L V6 that makes well north of 400 pretty easily.
In reply to wvumtnbkr :
EBay or Amazon turbo's start at about $125. Each. It is far simpler to use cast Iron manifolds off each side of a V engine than plumb the exhaust into one single manifold.
That way you can use 2 small turbo's (T2's ) which will spool up quickly.
You're going to need waste gate(s) so you can limit the boost to no more than 10-12 pounds they are about $50 each. Yes you can blend both sides into one feed so you only need one waye gate.
Plan on using E85. It's cheaper and safer for cheap stock engines
if you use E85 and keep boost reasonable you won't need an intercooler. .
If you have a high mileage engine that is still running well you won't even need to take it apart to open up the ring gap. Anything over 50,000 miles and 10 psi boost use it right the way it is.
There are plenty of UTube sources to help you figure out injector size and pump requirements.
Bottom line? The tune is going to make the car pleasant and reliable. That means you have to have it running semi decently before you put it on the chassis Dyno. Ask. Around, find someone who feels comfortable with your engine.
But watch some of the UTube video's. Get comfortable. Don't go for peak power! Seek a flat power curve and conservative timing. With the right fuel mixture.
AngryCorvair (Forum Supporter) said:
I think I would be shopping for takeoffs from an ATS-V, 3.6L V6 that makes well north of 400 pretty easily.
Me likey that idea.
I'm not really worried about hurting the engine. The 60 degree v6s seem pretty stout. However, I can't find a single instance where a 3900 has been turbod. Hence the questions!
Thanks yall!
In reply to wvumtnbkr :
I'd be looking at a single turbo in the "extra medium" sizing like a HX35 with a 12-16cm exhaust housing or a China GT3528. Small twins are great for response but bad for stock connecting rods. Push that torque peak higher, know and love E85 and be sparing with timing advance. This is the way for stock bottom end LS tomfoolery I don't see why this wouldn't work on your 3.9.
What you have, engine dimensionally speaking, is a Buick GN engine with better heads. Anything that works as a single turbo for one of those should be happy on a 3.9 Chevy. I am not sure what the exhaust manifold situation would look like, admittedly.
Like a dis?
https://www.ebay.com/itm/173603232390?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=NTDY0cRyQ8q&sssrc=2349624&ssuid=f3CQnRh7RLa&var=&widget_ver=artemis&media=COPY
Pete. (l33t FS) said:
What you have, engine dimensionally speaking, is a Buick GN engine with better heads. Anything that works as a single turbo for one of those should be happy on a 3.9 Chevy. I am not sure what the exhaust manifold situation would look like, admittedly.
Well, I made the headers that are on it now. It would be easiest to create 2 log manifolds pointed forward and hide the turbolater where the oil cooler used to be. Makes the exhaust packaging easier.
Turbo has to drain down into the oil pan unless you want to plumb in a scavenge pump. That is a valid way of doing it but it is remarkably expensive compared to just mounting the turbo higher than the oil level in the engine.
Good point. I gots lots of room in front. Just need to figure out exhaust while maintaining serviceability.
RacetruckRon said:
In reply to wvumtnbkr :
I'd be looking at a single turbo in the "extra medium" sizing like a HX35 with a 12-16cm exhaust housing or a China GT3528. Small twins are great for response but bad for stock connecting rods. Push that torque peak higher, know and love E85 and be sparing with timing advance. This is the way for stock bottom end LS tomfoolery I don't see why this wouldn't work on your 3.9.
For the street don't increase RPM's. Yes there is power up there but at what cost? First you'll need a camshaft. Which means tearing the engine apart. Then you'll need gaskets and••••• oh, while you're in there timing chain? Maybe sprockets?
If you keep the rpm to stock limits. The stock rods will easily live with 6-10 psi boost.
For the street you want bottom end pull. Not top end power.
Anybody got a cheap / free turbski they wanna offer?
wvumtnbkr said:
Like a dis?
https://www.ebay.com/itm/173603232390?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=NTDY0cRyQ8q&sssrc=2349624&ssuid=f3CQnRh7RLa&var=&widget_ver=artemis&media=COPY
Play around with this to give you an idea for sizing. Borgwarner Matchbot The compressor effieciencies will change between a nice Borg EFR turbo and the finest chinesium $130 will afford but it will get you close on turbine housing sizing which is probably the most commonly overlooked parameter on turbo selection that makes a huge difference in performance and behavior.
Too small of a housing the boost is going to come on fast, be hard to control and run out of steam up top. Too big of an exhaust housing and it will lag forever and be peaky with the power. I'm sure through your rotary experience you at least have some understanding of this but I've seen too many LS guys shove tiny twin turbos on it an 5.3 because twin turbos are cool or they "don't want lag" and then they squirt the rods out when they would have been better off with a "big" 75mm single and the right exhaust housing.
wvumtnbkr said:
Anybody got a cheap / free turbski they wanna offer?
How cheap are you talking? I'm going to shoot a text off to a buddy who is an even bigger parts hoarder than me.
turbos are so yester-tech nowadays.
you simply just need a $400 "pale of fuel"
https://youtu.be/s1iZ1-e1SfA
RacetruckRon said:
wvumtnbkr said:
Anybody got a cheap / free turbski they wanna offer?
How cheap are you talking? I'm going to shoot a text off to a buddy who is an even bigger parts hoarder than me.
Cheaper than a $120 ebay turbo. Challenge budget is real. Lolz.
wvumtnbkr said:
Anybody got a cheap / free turbski they wanna offer?
I do, traveling now and don't have time to write out all the details, but I'll send you an email Thurs or Fri when I'm back home.
How related is the GM 3.9 related to the GM 3800 which was offered with a Supercharger?
Sure SC is different power than T but with SC the added power comes on at lower rpm.
Is this 3.9L related ed to the 3.8L that was turboed in Buick Grand Nationals?
In reply to John Welsh :
They share the same bellhousing bolt pattern.
The 3800 is a 90 degree V6 dating back to when it was a Buick V8 in the 1960s. The 3900 is a 60 degree Chevy V6 that was an all metric clean sheet design in 1981ish.
The other thing with the supercharged engine is the intake train sticks halfway over the trans. I mean, I know Holden used it in some cars, and I'd really like to see how they managed that.
wvumtnbkr said:
Anybody got a cheap / free turbski they wanna offer?
for you, yes. i have two brand new small-ish ChiCom turbos i got for four hours of labor cutting up and scrapping an old stock car chassis at whiskey_business' place. i would be happy to give them to you for the labor you put in on MonZora seatbelt. so i think the budget would look like:
4 hrs labor at w_b's = 2 angry turbos = angry seatbelt = 2 wvumtnbkr turbos
and of course i would cover shipping since it's my bad for not bringing them to the challenge
EDIT: my labor was at MI minimum wage (per challenge labor trade rule) of $9.45/hr
EDIT2: not an inside deal. read first paragraph of first post in this thead: https://grassrootsmotorsports.com/forum/2000-challenge/boost-everything-challenge-priced-new-turbocharger/135546/page1/
