saccitycorvette

iTrader: (3)

Hey everyone I just finished a rear mount turbo on my 97 lt1 camaro. It have a forged 383, cc305, fmic, mp t70. Well the turbo spools loud but it doesnt make much boost at all. Like 2psi and 0 psi on the 2 step set at 4500 rpm. I checked all the t bolt clamps and checked the bov but I dont see any issues. And you please list some things I can check?

Thanks,
Matt

itsslow98

iTrader: (18)

Definetly a boost leak somewhere. Find a smoke machine if possible and test it that way. Are you getting boost off the 2 step or just when your on the 2 step?

saccitycorvette

iTrader: (3)

Its still reading -1 pound of vacuum on the 2 step. And I will see about 2 psi on the road. Im using a aem tru boost for the controller

itsslow98

iTrader: (18)

Check every connection again and make sure you have the vacuum lines for the boost controller and bov correct. 2 steps can be tricky because to build boost sometimes you have to pull a lot of timing out with stick cars and add a lot in with an auto to get it to build boost.

saccitycorvette

iTrader: (3)

Yeah I understand that and im not pulling any timing on the 2 step but im still only seeing 2 psi on the street. My wastegate spring is 5lbs so I should at least see that right?

smokeshow

iTrader: (17)

That turbo is definitely too small by anyone's standards. What size exhaust housing? Try building boost at low rpm. For example, keep it in high gear and put your foot to the floor and let it build up slowly. If you see more boost at low rpm, then your turbo is simply too small.

Johnv

Is your wastegate referenced at the manifold or turbo compressor ? If at the compressor that is probably all you'll see at the manifold with a 5psi spring.

saccitycorvette

iTrader: (3)

Yeah I know its too small. This is my first turbo build so I bought the turbo then found out it was too small. The waste gate is on the compressor but im using a aem tru boost to add more boost

smokeshow

iTrader: (17)

If your boost controller is cranked all the way up, then you would theoretically see 10psi... I would expect a few psi drop from the compressor to the manifold, but not 8psi. That is if the compressor is keeping up. If not, which is very likely, then you'll have to run a larger turbo to gain more boost. Try that low rpm/full throttle idea I mentioned earlier. That'll tell you if the turbo is done.

Which intercooler are you running?

saccitycorvette

iTrader: (3)

Ok I will try that tomorrow. Its a big a2a front mount. Its the size everyone is sticking in the front of camaros. What turbo would be good for this set up. Remember its a rear mount daily driver m6

smokeshow

iTrader: (17)

How much power are you looking to make? And how much would you like to spend on a turbo? That camshaft is not optimal for a turbo, but you can make do with it.

saccitycorvette

iTrader: (3)

I want to make as close to 650rwhp as possible and spend as little as possible. I was even looking at the on3 turbos because I hear good things about the for the price

smokeshow

iTrader: (17)

Got it. Well I'd have to recommend the S475 in a T4, 1.25AR housing. I am assuming your current turbo is a T4, so it would bolt to that flange. The downpipe would have to be modified a little bit though. That can be had for $900. The Magnum turbos which replaced Master Power should bolt right in with no modifications, although I would recommend talking to a sponsor/turbo retailer to make sure. The Magnum 80mm T4 1.22AR is a bit more expensive at around $1100.

saccitycorvette

iTrader: (3)

Ok I will look into those. Yeah im a t4 flange and I can make a new down pipe to problem. Thanks for the info

saccitycorvette

iTrader: (3)

I will try that low rmp test tomorrow to see if it makes boost or not

THADD

iTrader: (12)

What brand intercooler? If its a cx or a cheaper intercooler I have heard they can be bad for dropping boost. And if you only have a 5 lb spring, then....

saccitycorvette

iTrader: (3)

@THADD Its like one of the cx racing intercoolers.

saccitycorvette

iTrader: (3)

@smokeshow I put it in 6th gear going like 60 and punched it and it only makes about .6 psi then I dropped it to 4th and did a pull and only maked 5-6 psi. This is with the tru boost maxed out also

tta656

iTrader: (5)

http://www.gmhightechperformance.com.../photo_03.html

I know this may seem dumb,,but did you possibly get a turbo that requires an INTERNAL wastegate like in this pic.... the small hole open like that will not build boost,the hole blocked/closed by an internal wastegate will allow boost to build..

you have to be able to hear the boost pressure escaping somewhere if you cant build any boost

Preston99WS6

iTrader: (7)

I wouldn't run a BW unit for a remote mount its very large and heavy so it would hang lower and be a pain the a$$ so support. Dont get me wrong BW units are awesome but are way to heavy and will be a huge headache. I had a STS kit with a garrett GT76mm turbo, .96 A/R 68 mm turbine. I made 680rwhp with my setup. The Mp 70 is Not the problem as my garrett was almost the same size just a larger compressor .

Next issue of no boost. You need to perform a boost leak test. Here is how you do it.

1. Measure the inlet to the turbo. Probably 3.5 or 4" if I was to guess.
2. Go to Home Depot or Lowes and buy a PVC pipe cap of that size. Buy a male air compressor fitting and a 1/4" NPT pipe tap.


3. Get a coupler in the same size as the turbo inlet.
4. drill a hole in the center of the pipe cap. and thread the air compressor fitting into it.
5. Install the cap with the silicone coupler and clamp it down where the air filter goes.
6. Hook up air compressor to the pipe cap you just built and turn regulator down to 10 psi.
7. Check for leaks by listening and using soapy water all the way from the turbo to the intake to head seating surface, tighten/repair
8. Increase pressure to whatever boost level you plan to run plus a few extra pounds for good measure.

This setup will probably cost 25 dollars to build and can and should be used anytime you have to remove couplers. It also removes all of the guess work out of finding boost leaks since you can hunt them down in your driveway.
Good Luck.