getting some mixed info on turbos

[Plague_oc]

Well my plan now is to run a turbo straight 6 (as opposed to n/a LT1) and Im having trouble deciding which turbo is right for me. I am planning for 300hp. I have recently been reading about holsets here and it got me to thinking if it would be a better idea to switch out the stock T3 and add a Holset HY35 or something similar.

 

Here is where I start to sound dumb: I am getting mixed info on what a larger turbo would result it. If I were to run both these turbos at 15psi, would the T3 perform the same as a larger turbo, or would the larger turbo be able to displace more air and add more HP at the same psi?

 

Also (most importantly), how does a larger turbo impact strain on the engine? Would a large turbo be able to reach a greater HP at a lesser psi and put less strain on the engine? Or would it not make a difference as the same amount of air will be displaced...If I could reach the same HP and not put as much strain on the engine than with the stock T3 than I would rather buy a larger one.

[gearheadstik]

I think you right in saying that the larger turbo does make more power at the same boost, but it does take longer to spool...I have only had my car running a little while and love it but still tunning so I dont know if these numbers will change...I hope they do for the better. I'm using a holset HE-351 which looks identical to a HY35W. I think I read there is a difference in intake compressor housings, maybe mines a little larger. Back to the facts.... I noticed in this post http://forums.hybridz.org/showthread.php?t=123015 that nish states

"Flooring it at 2500 rpm

 

2500 = 4psi

2600 = 5psi

2700 = 6psi

2800 = 7.5psi

2900 = 8psi

3000 = 9psi

3100 = 10psi"

But this depends on what gear you kick it in too... the higher the gear the quicker it seems to come in.. mine in a 4th gear roll looks more like this

2500=1psi

3000=6psi

3500=11psi

4000=12psi

4500=14psi

5000=15psi

When the boost comes in it feels like the tires start to burn....but I do need a new clutch and a lsd...Sunday was my first day at the track and I ran a 8.8 in the 1/8... That was fast enough to eat a newer gto and two mustang gt's, one spraying...don't know how much..I do have a EBC...I only hope to get faster when I get some new parts... my setup is almost the same as big-phils.. NA-p90 38lb ford injectors

[Tony D]

JeffP ran on a dyno early last year, and with the GT35 he was running 8psi and making over 380ft-lbs to the wheels at 4500rpms....engine will turn to 7500rpms.

 

Build the engine to flow first, then size the turbo for the horsepower and spool characteristic you want, and you can easily have a car that will make that kind of horsepower at low boost levels. The response is more linear, and "N/A Like" thought the way the power rushes on as the revs rise seems to be counterintuitive.

At these boost levels, exhaust manifold pressure is equal to intake manifold pressure, so it's flowing well through the turbine, minimizing parasitic loss from preturbine backpressure and possible exhaust reversion or decreased cylinder scavenging.

[Plague_oc]

Alright, so I guess I will upgrade my T3 after I get my turbo setup running. On a more offtopic subject, how would a stroker be affected by a turbo? I was considering putting in a LD28 stroker for the extra torque which is .1L bigger but I don't know how much of a difference it would have performance wise. Would .1 really be a significant upgrade?

[OlderThanMe]

You get TORQUE with the LD crank.

[Plague_oc]

regardless of the L I will see a significant increase in torque if i use the LD28 crank?

[Tony D]

That is what JeffP is running. 0.040" overbore to mostly unshroud the valves, and a stroker crank for more torque.

 

Power Peak happens on his setup somewhere around 7300rpms.

[Pyro]

If you are only building a 300hp street engine then I would use a stock T3 turbine with a TO4B 50 trim compressor. Will need a turbo spacer.

 

Then use a stock turbo block and head and stock compression ratio (this will make your life much easier). A lot of pit falls when building a stroker plus cost go up dramatically and so does the compression ratio which makes it more difficult to turbo charge safely.

 

Install a bar & plate intercooler, external waste-gate, megasquirt with ignition control, 2.5 inch down pipe, and 2.5" mandrel bent exhaust with a 2.5 inch dynomax super turbo muffler.

 

The above combo will be fairly easy to build, will make great low rpm torque, and about 300hp at the rear wheels. Not the fastest turbo z ever built but a very fun car to drive on the street! Lots of tire smoke. Should be able to run a high 12 second 1/4 mile.

 

If you plan on using the stock cam then the stock T3 turbine works well. The stock cam and stock turbine have the same power band (a good match). Using the stock turbo cam with a high flowing turbine makes the useable power range very small. A NA cam will give a turbo engine another 500 rpms of useable power due to 8 more degrees of intake duration.

 

A clutch upgrade will also be required.

[Clifton]

I would figure ou thow much boost you want to run. Lets say it's 15-17 psi. With a stock T3 or T3/4 with a stock T3 turbine you will be making a little over 250 rwhp. With a larger T3/4 or full T4 you can be making 350rwhp.