C5 rear mount turbo question?

**rthackwray** · 12-16-2015, 11:59 PM

C5 rear mount turbo question?
I have a 1998 C5 corvette with 232/234-112 lsa futral f14 camshaft,low lift..I believe 585 lift on each side.The car is 4l60 with Circle D 3600 stall and 3.90 geared.I recently added a rear mount 76mm turbocharger with intercooler.I am using stock manifolds with vbands welded on and entire turbo build is fabricated.My heads are stock and unmolested.I believe 806 castings but do have the valvetrain upgraded with dual springs,etc.Intake is a stock ls1 and TB is a bbk 85mm with spacer..My question is..Will I be able to achieve over 550 rwhp with this combo and rev it to 6k even with the positive overlap of the camshaft?My car is at the tuners at the moment..The car is dropping off drastically on power @ 5k rpm at only 5lbs of boost.The fueling,afr, and pressures are ideal as my tuner tells me.Any and all info is appreciated.I just want my car to at least rev to 5700 before dropping off.I believe the cam is rated for 6500 rpm.Its being tuned on E85 and has walbro 450lph e85 pump with hotwire and siemens deka 80lb high impedence injectors.Thanks guys

**rthackwray** · 12-17-2015, 07:20 PM

Nobody?Really?

**FasstChevys** · 12-18-2015, 08:02 AM

Honestly, I think 550 to the wheels is a stretch @ 5 psi. Especially if you haven't done anything to the heads. I'm surprised you're only achieving 5 pounds of boost with being intercooled. Something doesn't jive.

I'm also curious why you care about what the engine will rev to. What are you trying to accomplish with the car?

**35th-ANV-SS** · 12-18-2015, 03:01 PM

I'm reading his post as the car only makes 5psi, not that he was expecting to only achieve that. I could be wrong.

**RONS98TA** · 12-19-2015, 04:46 AM

Sounds to me the car should be able to make 500+ hp with no problem. If you are only seeing 5psi of boost, the you must have a clamp or 2 loose somewhere, causing a boost leak. Recheck all your clamps or you might even want to go as far as doing a boost leak check. Use an air compressor and a gauge and check how much boost the cold air intake tubing can handle. I would guess you should be able to make at least 15lbs of boost with that setup.

***SMWS6TA*** · 12-19-2015, 06:52 AM

Correct spring for the blow off valve?

**FasstChevys** · 12-20-2015, 06:40 AM

Originally Posted by 35th-ANV-SS

I'm reading his post as the car only makes 5psi, not that he was expecting to only achieve that. I could be wrong.

You're right, I didn't read it correctly. At the same time, there's a lot more answers to questions needed on this one.

**FasstChevys** · 12-20-2015, 06:44 AM

Originally Posted by RONS98TA

Sounds to me the car should be able to make 500+ hp with no problem. If you are only seeing 5psi of boost, the you must have a clamp or 2 loose somewhere, causing a boost leak. Recheck all your clamps or you might even want to go as far as doing a boost leak check. Use an air compressor and a gauge and check how much boost the cold air intake tubing can handle. I would guess you should be able to make at least 15lbs of boost with that setup.

That 76 should take him way past 500 to the wheels. There's definitely issues. With no work done to the heads, the boost should go through the roof with that 76.