Turbo Advice for Series 2 3800

[SlowFiero]

I also have a few 245mm converters kicking around if you want a few cores.

 

[Dusty Bradford]

I also have a few 245mm converters kicking around if you want a few cores.

Not really much demand for them but if someone needs a higher stalling converter for the 4t65, that would be the core you want to send in. Thanks for the offer.

 

[bison]

How much boost is a 6076 going to need for ~450 rwhp? 610 fwhp would be pretty close to 450 rwhp, and that is the rated max for the 6076.

Less than 23 psi. I made roughly 450whp with a 6176 on a thrown together LC1 with only a little bowl clean up. The engine has less than 8:1 and the turbo has the small 3 bolt Garrett .63 ex housing. You should be able to hit 450whp at 22psi. Fwiw the 6176 made 500whp on the same engine with more boost. Those hp ratings that are thrown around dont mean chit. 1mm more in comp inducer isnt going to change much unless you are running it with the wastegate closed all the way. Id run a T4 and get a PTC NL converter

 

[bison]

With the smaller turbo wouldn't I need to run more boost to make the same power as the 62mm? That would be worse with the compression than the 62mm at a slightly lower boost. Also I haven't seen anywhere that the 60mm is cheaper than the 62.

I would like to get a 211/212 cam as I believe it would work well without pushing the powerband too high. The heads are decent right out of the box on the series 2 engines. Unfortunately they have discontinued the st2 and st3 cams that I think would be good. So it is either a st1 (206/206) or at st4(224/218) or st5(230/224) that is available. People say that they are all streetable on this engine but I don't really want to be shifting at 6500+ rpm anymore. Also think the bigger cams would probably be better with a larger 67mm+ turbo to feed the high rpm. I am trying to see if the original producer of the cams still has a st2.

I believe your ptc converters are built on our 245mm cores. If the Neil Chance converter doesn't work out I will probably go with a ptc. I know they are building them for the 4t65 now through triple edge performance and Dave there highly recommends them.


Where can I find the T3 to 3" vband flange?

The larger compressor wont do anything to make more power at low boost unless it was being run on the edge and heating the charge air excessively. The engine has to need the airflow potential of the turbo for it to make more power. Otherwise it does nothing. Ive been testing turbos and found that even with some reportedly restrictive ex housings the larger compressor change did absolutely nothing for power nor did the bigger ex housing. Bigger just spooled slower and cost more. The largest one i tested which was a BB 7680 actually had a slightly higher charge air temp than the 6176 and it spooled like a turd. On an engine that could use the airflow it woudl make a lot of power but not this one. The 6176 has been the most potent one ive tested so far on that combo. Nothing has made more power and the only thing that spooled faster was the 44 but it choked of a lot with the small ex wheel. You should be able to order whatever lobes you want. Check the comp catalog. I would not even think about anything over 210*@.050 unless you are planning on a 3000+ stall at zero boost/vacuum and plan on running faster than 135mph trap speeds with the lightweight car. 224/218 will be a pig until you hit at least 4800rpm or preferably higher and throw a lot of boost at it. Thats a mid 9 sec grind for a hard running 3.8.

 

[bison]

I have a Neal chance converter now that will foot stall to 2500, flash to 4200, and gets 10% slippage around 6000. Still not spectacular considering my actual whp at this altitude is only 335, and car weighs 3000 lbs. I can't imagine what the slippage is like on a 3600 lb grand prix with 400-500 whp with a turbo.

A lot of room for improvement there.

 

[bison]

This way I can make the same power, with stock GM parts, with plenty of replacements around.

You should start posting this in the other forums because the dumb asses there seem to think that they need to keep throwing parts at their car to make them perform. Especially bigger turbos. Which do nothing but lighten their wallets.

 

[SlowFiero]

So you would suggest a 6176 in a t4 housing? Which a/r in a t4? What kind of stall would that require. Part of wanting the billet was the lighter comp wheel supposedly needing less stall than the 61 cast wheel. And supposedly more room to grow up top.

A 6176 is around 850 for a journal, 6262 billet is 899, hartline had 10% off as well, so it could probably be had for around 810. Would you still suggest the 6176 over the 6262?

Thanks for your help. I was hoping that you would pop into this thread, as you really seem to know what us going on with turbo 3.8s.

Would a 206/206 be a good cam to consider?

 

[kshef]

Would a 206/206 be a good cam to consider?

yup

 

[Dusty Bradford]

SlowFiero. Is your current converter based on the 245 or the 258 core? Is the 2500 stall that you are seeing at 0-1psi of boost?

 

[SlowFiero]

It is a 245 mm core.

I can get ~2500 rpm on the foot brake, then the engine pushes through the brakes. I can get that rpm either loading up against the brakes, or WOT on the 2 step. I have the 2 step set to 2400, if I set it to 2500, the car with creep. On the 2 step I have 12-13 lbs of boost (roots blower), on just the foot brake against the converter I have probably 0-1 lb of boost, I can't get into the throttle far enough to close the bypass valve in the blower.

I was running originally a pontiac sunfire converter, and could stall to 2800 rpm before pushing through the brakes. I then bought a ZZP 3000 stall, and could get 2400-2500 rpm. I swapped it out for a ZZP 3500 stall and could once again get 2800 rpm, flashing to ~4500 rpm. Now I have a Neal Chance converter that I had built, and again I am back at 2400-2500 rpm, flashing to ~4100 rpm. None of them have achieved less than 10% slippage without spinning to atleast 6000 rpm. I think the best I saw was ~5% slippage at 6600 rpm. I have data scans for all these converters if it is something you want to look at.

I would guess the stall speed is due to the weight of my car(3050 race weight), and the not so great brake setup on the Fiero. I have upgraded to 11.25" rotors, but it is 4 wheel disk, and with the front bias, the rears don't have the holding power to hold the car on the line. The fronts will stay locked, and slide accross the ground once I push through the rears.

What would a converter with a proper turbo stator, furnace brazed etc cost me? What about anti-ballooning. Do you do a billet cover for the 245mm? The converter I have now is setup for a M90 blower, with a 217/225 duration cam, I imagine it won't work all that well for spooling a turbo with a 206/206 cam or I will drive right through it once the turbo spools.

Thanks for your time.

Cory

 

[Dusty Bradford]

It is a 245 mm core.

I can get ~2500 rpm on the foot brake, then the engine pushes through the brakes. I can get that rpm either loading up against the brakes, or WOT on the 2 step. I have the 2 step set to 2400, if I set it to 2500, the car with creep. On the 2 step I have 12-13 lbs of boost (roots blower), on just the foot brake against the converter I have probably 0-1 lb of boost, I can't get into the throttle far enough to close the bypass valve in the blower.

I was running originally a pontiac sunfire converter, and could stall to 2800 rpm before pushing through the brakes. I then bought a ZZP 3000 stall, and could get 2400-2500 rpm. I swapped it out for a ZZP 3500 stall and could once again get 2800 rpm, flashing to ~4500 rpm. Now I have a Neal Chance converter that I had built, and again I am back at 2400-2500 rpm, flashing to ~4100 rpm. None of them have achieved less than 10% slippage without spinning to atleast 6000 rpm. I think the best I saw was ~5% slippage at 6600 rpm. I have data scans for all these converters if it is something you want to look at.

I would guess the stall speed is due to the weight of my car(3050 race weight), and the not so great brake setup on the Fiero. I have upgraded to 11.25" rotors, but it is 4 wheel disk, and with the front bias, the rears don't have the holding power to hold the car on the line. The fronts will stay locked, and slide accross the ground once I push through the rears.

What would a converter with a proper turbo stator, furnace brazed etc cost me? What about anti-ballooning. Do you do a billet cover for the 245mm? The converter I have now is setup for a M90 blower, with a 217/225 duration cam, I imagine it won't work all that well for spooling a turbo with a 206/206 cam or I will drive right through it once the turbo spools.

Thanks for your time.

Cory

The lighter weight is actually working in your favor. A heavier car will have more slip.

I can do a billet cover but that doesn't gain anything from a performance perspective. Everything I do has anti-balooning plates and furnace brazed fins. What you are experiencing is just the nature of the cores you have to work with on that trans. The 245 can get loose enough to spool a turbo but they aren't great at coupling real well unless you can turn enough rpm to offest the stall. Which is exactly what you have experienced.

May be best to send me one of the other cores you have used. Say one that you know stalls 2500rpm and slips x %. I can look at it and see if it can be modified somehow to get closer to what your looking for.

 

[SlowFiero]

Been looking around. And think I might be looking at a 6057 billet now. Should work well with my current converter, and be able to reach my power/ET goals. Would a ported S cover be worth it, or just a straight S?

So T3 0.63 or T4 Tang 0.58, that is the question. Either way it will be V-band outlet. I have heard a T4 0.58 will spool better than the T3, and make more top end, but that could be BS, something has to give somewhere right? The exhaust housing is really where I am lost. Don't know what is going to work, and what will not. Anybody have a suggestion?



Thanks Dusty, the only converter I currently have that I have run is the Neal Chance in the car. The others I have sold off, or scrapped. If whatever turbo I choose doesn't work with the current converter I will probably look at having you build something next winter.

 

[Dusty Bradford]

Been looking around. And think I might be looking at a 6057 billet now. Should work well with my current converter, and be able to reach my power/ET goals. Would a ported S cover be worth it, or just a straight S?

So T3 0.63 or T4 Tang 0.58, that is the question. Either way it will be V-band outlet. I have heard a T4 0.58 will spool better than the T3, and make more top end, but that could be BS, something has to give somewhere right? The exhaust housing is really where I am lost. Don't know what is going to work, and what will not. Anybody have a suggestion?



Thanks Dusty, the only converter I currently have that I have run is the Neal Chance in the car. The others I have sold off, or scrapped. If whatever turbo I choose doesn't work with the current converter I will probably look at having you build something next winter.

OK. Keep me posted.

 

[Turbo6Smackdown]

The larger compressor wont do anything to make more power at low boost unless it was being run on the edge and heating the charge air excessively. The engine has to need the airflow potential of the turbo for it to make more power. Otherwise it does nothing. Ive been testing turbos and found that even with some reportedly restrictive ex housings the larger compressor change did absolutely nothing for power nor did the bigger ex housing. Bigger just spooled slower and cost more. The largest one i tested which was a BB 7680 actually had a slightly higher charge air temp than the 6176 and it spooled like a turd. On an engine that could use the airflow it woudl make a lot of power but not this one. The 6176 has been the most potent one ive tested so far on that combo. Nothing has made more power and the only thing that spooled faster was the 44 but it choked of a lot with the small ex wheel. You should be able to order whatever lobes you want. Check the comp catalog. I would not even think about anything over 210*@.050 unless you are planning on a 3000+ stall at zero boost/vacuum and plan on running faster than 135mph trap speeds with the lightweight car. 224/218 will be a pig until you hit at least 4800rpm or preferably higher and throw a lot of boost at it. Thats a mid 9 sec grind for a hard running 3.8.

So I am learning stuff. Sweet. (Thanks Bison. I've payed attention to your posts over the months, and started picking up on ****. Slowly but surely)

 

[SlowFiero]

Under the advice of Patrick, I ended up ordering a 6262sp in a t3 0.63 v-band housing. Also ordered a 46mm precision wastegate, drain hose kit, v-band flange and clamp, some stainless 1.75", 2.5", and 3" u-bends, a t3 flange, exhaust manifold outlet flange, and a 3-2.5" reducer to build all the hot side piping.

If the weather ever clears up I will drive down to the border and pick it all up in the next or two and get started.

Still need a a/w Intercooler, cam, intake plumbing, oil feed line and filter.....

Thanks for all your help,