TPI intake not adequate?

[vetteboy86]

I have been having issues with some aspects of my car. I went with the stroker and mild cam, had the heads ported, and put a tpis bigmouth on the motor. I also have siamesed runners, and hogged out plenum.

I have been conversing with several people about my motor falling on its fact around 4800 rpms. I thought it was fuel, so I upgraded fuel system, I then turned to spark, so I upgraded ignition. Now I am thinking it is inadequate air flow, which would actually cause the motor to be rich?

I bought a wideband so I will know exactly what is going on. I may be jumping the gun here, but it is starting to make sense.

So my first feelings are towards a super ram, because my car is an automatic, and I dont have gears done yet. The only real thing holding me back is the install. Anyone out there recently install one? I have read through old threads, and most are filled with bad feelings.

Thanks,
Craig

 

[racsluos]

The general consensus is that if you want to spend a lot of time above 5000rpm, you will be happier with a SuperRam, StealthRam(requires mods), or MiniRam. Only thing is that to get the most out of these, heads and cam are fairly important.

 

[SPANISHVETTS]

Which camshaft do you have?

Thunder's 383 pulls strong to about 5100 with the same intake that you are running. What TB are you using. I have a 52mm. I never tried the 383 with the stock TB so I can't say if it makes a difference or not.

Looking at the cost of intake systems forced air induction makes financial sense. If I do any more mods to Thunder he will get a supercharger.

 

[KANE]

...I have been conversing with several people about my motor falling on its fact around 4800 rpms. I thought it was fuel, so I upgraded fuel system, I then turned to spark, so I upgraded ignition. Now I am thinking it is inadequate air flow, which would actually cause the motor to be rich?...

What do you have your FPR set to? Have you installed an adjustable fuel pressure regulator? How about some data logging to determine exactly what is going on- then you could burn a custom chip.

I have as similar set up running stock L82 heads (no porting though). I've had no issues with my similar set up up to 5500.

 

[vetteboy86]

I put the wideband in the other day, and recorded AFR's around 11 or so at WOT. I have 30# injectors and my fuel pressure is set to 45 psi (vacuum unhooked).

Also, I just have a 48 mm TB. Some say the 52 is way over kill. I do have all the equipment to do custom tune. So I think I may try to dial it in, and then add some more go fast parts, like the super ram.

How much will I gain. I think the cam is 218 int 224 exh at .050. I can check for sure when I pull the part number.

 

[KANE]

... I have 30# injectors and my fuel pressure is set to 45 psi (vacuum unhooked)...

I think you may have an issue with the injector size against your programing- they may have too wide a pulse width and its not aligned with your fuel & spark tables.

What CID is your mill? Are you still running MAF?

 

[vetteboy86]

I changed the injector constant, and thought that would take care of the calculations, because before the 24# injectors were pretty much at there limits as far as duty cycle is concerned. Yes I am still running MAF.

 

[speedmaster4]

the tuned port rules for pretty appearance, maybe prettier than a polished 6-71...and the tpi intake is superb for ''normal'' street driving ( 4000 rpm max)...but it fails in high rpm use (my experience at least with 355 c.i. and 406 c.i.)...for stong pull all the way up to the rev limiter, try a modded lt1 intake (works for me)

 

[vetteboy86]

I think I am gonna probably go with a mini-ram. From everything I read, I can use the fuel rail I have now, and the intake manifold I have now also. I am really looking at a standpoint of a happy medium. From what I read, the super ram allows for higher revving hp but not at the expense of all the low end torque.

 

[SPANISHVETTS]

What are you rear gears?

The mini-ram will lose a bunch of torque below 3000.

 

[vetteboy86]

That is what I have heard. However I have read that the super ram bridges the gap in a sense. Right now the gears I have in the car are 2.73's.

 

[KANE]

That is what I have heard. However I have read that the super ram bridges the gap in a sense. Right now the gears I have in the car are 2.73's.

The LT1 and Mini-ram work well, although the HSR would be best to keep your torque. I've heard you'd have to reduce the height of the plenum as it seems they don't fit well under the C4 hoods.

 

[vetteboy86]

I have read about vacuum leak problems, and fit. However hood clearance is something I wasn't aware of. This does raise cause for concern, because I really would hate to modify the hood, or buy something else.

 

[SPANISHVETTS]

What exhaust headers, cats and mufflers are you using? I have long headers with 1 3/4¨ primaries, 3¨ true duals w/Randon hi-flow cats and Targa mufflers.

Again I have never run the 383 with stock exhaust so I can't say how bad the stock system was but it has always been my experience that no intake would work well with an exhaust as restrictive as GM hung under our EPA friendly Vettes.

 

[vetteboy86]

I have the TPIS long tube headers, into a 3" y-pipe, back out a 3" y-pipe to dynomax ultra flow mufflers.

 

[SPANISHVETTS]

I have the TPIS long tube headers, into a 3" y-pipe, back out a 3" y-pipe to dynomax ultra flow mufflers.

Excellent