So I'm really conflicted about this. I have a 355 (LT1) all forged with low compression and some ported LT1 heads. I really want a turbo that will spool fast but that is still capable of making around 1000hp. My real question is, will two smaller turbos spool faster than one bigger one while maintaining the same potential for power? Just need some suggestions on what worked for you guys.

Thanks,
Jeremy

 

One well tuned turbo.

 

Absolutely wrong. A properly sized single will work just as well as twins. Unless you don't know what you're doing, a single turbo will not have lag. You also have the issue of cost... twins=two turbos=more expensive up front, more expensive to rebuild, and more piping. A single will work equally as well for a street car and allow you to retain your A/C.

 

A/C...not important (as well as non-existant) and my car had its feelings hurt when you called it a street car....it prefers "street driven" race car.

But all turbos have lag right? unless I ran my y-pipe into the turbine it must have some lag. And then I have always had this sense of balance that I like to indulge....It just doesnt seem right to have more back pressure on one cylinder bank than the other.

And as for why I dont use a supercharger....I dont know, I just want a turbo, it leaves more room for growth in the future.

Good info though, keep it coming.

 

Well we should really get some people in here that know what they are talking about,, from the looks of it but i have some hands on experience. For example the person building my kit has a 94 vette with a 355 low compression and everything. With an automatic trans 4l60e he spools by the time his foot can hit the floor. so pretty much under 2000rpm. He uses one gt76 and that turbo is capable of more than 1000hp. so think about that and if you are serious then i would look into a PTK turbo kit. email or im me if you have any questions. ( also im building a kit with a gt42r that should spool by 2800 rpm and is good for 1300 hp or so)

 

One well tuned turbo.

 

So there seems to be some conflicting views? I wouldn't mind seeing one of those PTK kits to see what their headers look like. Keep in mind everyone that I'm not buying a kit (college kid budget ) I'll be fabbing all the piping myself so pictures would be real helpful.

 

what bias to one side of the engine? in a single turbo setup, both headers still feed into the tubine and share the same pressure... there's a ton of information in this forum if you spend some time searching and reading.

 

sorry 1/2 and 1/2 but i dont think you really know what you are talking about in this situation and you should really stop trying to persuade anyone to do something you know nothing about.
Oh yeah i forgot it only makes sense to run all 8 cylinders into the turbo if not you are retarded. sorry

 

That does make more sense then. I always just assumed people ran only one header/manifold into the turbine for simplicity sake. You see, thats why I ask questions

So the 76mm turbo then, assuming I wont ever go beyond 1000hp is that a good choice? And what is the major deciding factor in how quickly it spools? Is it all dependant on the cam?

Thanks guys,
Jeremy

by the way, I get what you're saying 1/2 and 1/2, and in an ideal situation I guess twins would be more efficient at making horsepower, just like 4 small valves are better than 2 big ones. But I guess its just not as practical and not necessary.

 

One well tuned turbo.

 

These engines move enough air to spool a big turbo quickly. A friend with a T-72 on a 383 builds 3-4psi by 1400rpm. I have a T-76 and expect at least 5-6psi under 2000 rpm and 700-750 rwhp on 93 octane pump gas. (This same turbo put down 977rwhp/1022rwtq on a mustang using C16)

The thing that determines spool-up is the is the turbine A/R, not the cam. A smaller A/R will make it spool faster, but will keep more pressure in the exhaust side, limiting high rpm power.

You can keep all accessories and go up to a T-76GTS with these cars pretty easily. With the right combo, that'll take you well into the 900-1000fwhp area, build some boost under 2000rpm, and hit full boost by 3000 rpm. Unless you plan to go beyond that, twins will be nothing but a headache and extra $$ down the tube. (jmho)

 

Well, unfortunately the motor wont handle much more than 1200hp. But I guess you talked me into it...T-76 it is. I appreciate all the input guys.

Jeremy

 

Roadies put that really well. Screw Twin Turbos.

 

I actually did a little cost comparing when I was selecting parts for my project. Two smaller turbos cost about the same as a single large turbo. I selected two PT-61s vs a single PT-76GTS. The main reason I would pick a single for an F body is for space.