Recently had my car dynoed after some work. The power started dropping off @ 5k rpm and it does not like to rev past 5500. I am wondering if the turbo is choking off the motor, or if the cam is as much the problem. Brief rundown of my setup, 347, cnc'd victor jr's , b cam, and hellion kit with 66mm upgrade, .96 a/r. I have not done a compression check, but was told approx. 9:1. I would like to change one or the other, as I am not really excited about putting much more money into the car.

 

What about your valve springs?

 

I had the same porblem and it ended up being a bent pushrod.

 

Oh yeah, what are you running for an ignition and plug gap?

 

Kinda a small turbo for that engine. 347 cubes and CNC'd Vic jr means alot of air IMO. A 76 mm turbo would be more like it. I have no idea as to what B cam specs are and you didn't mention boost level... I would lean towards a bigger turbo. Just a thought.

 

B-Cam does not like to rev. I would check that, but i'd do the basics first.

 

ignition is msd 6al, plugs are gapped @ .028, and running between 15 and 25lbs. depending on what fuel I am running. I guess I will pull the pushrods, and check the springs first. I have a feeling I need a 76mm on the car. I was thinking of jumping on the bandwagon with the s400, however I hate to start pulling the car apart again. I just got the car back together!

 

did boost hold steady thru the entire pull?

 

Even if boost doesn't fall off you will hit a wall as it goes out of its efficiency range. Just blowing hot air. Yeah 15 to 25 lbs yikes you need a larger turbo. I think you will notice a nice increase in power. The sx400 t4 flange wouldn't be any more fabbing than a t76 type turbo. You have more housing options as well. .90, 1.0, 1.10 and 1.25. in T4 and T6 is upgradable to 80mm quite easily. That is why I bought one myself in a T6 because I am setup for that. Dave is a good guy and put up with alot of questions from me over a long period of time.

https://www.theturboforums.com/smf/index.php?topic=93909.0

Here is a rouph estimate of your engine at 15psi and comparing S400 to a T66. Just thought I would help making a informed decision.

 

Thanks for the info! I thought the sx400 was t6 flanged only. I think I am going to call Dave @ Majestic and get one ordered.

 

What manifold?

 

systemax

 

Bcam is too tiny. And the 66 should be okay for a street car.

 

i would say B cam also....thats like one step up from stock.....not made to rev.....F cam is suppose to be better for turbos

 

does e-cam have similar issues... I was told it would be better for street use, and kept it from my n/a setup. I know they are great for superchargers, so I would be wondering if an e-303 would significantly choke a 306 on afr heads, and 1.71 rolller rockers. Just currious. Forgive me if this is kinda a threadjack.

 

I'd say turbo is out of steam on that motor as well....347's want too eat! I am doing the same but for expermentation purposes for self satisfaction and helping others with my trial and errors..