What Turbos do you Recommend?

[wilkinshc]

Hi,

What size turbos would you recommend? I have 454 with 10.2 compression, block is (4 bolt slayed outer holes,forged crank, forged rods with 7/16 bolts, and forged pistions) alum. heads(intake valves 2.25 exhaust 1.88- 110cc) , cam is .640/.598 lift- 114 degree lobe separation with 1.7 roller rockers. It will be street driven mostly. I want to run a twin turbo at 5-8 lbs of boost. Was thinking no intercooler but using water/alcohol injection if needed. It is fuel injected (has 38 lbs injectors but planning on going with 60lbs), I have dual walbro 340s in the gas tank and I plan on use a FAST setup. I would like to be in the 700-800 hp range. Redline is 6200 rpm and would like boost by 2500 rpm. It's backup up by a 200r4(well built) and 12 bolt rearend(373 gear) . Running 13in wide tire.

Thanks for any suggestions.

Chuck

[John Wilde]

Originally Posted by wilkinshc

Hi,

What size turbos would you recommend? I have 454 with 10.2 compression, block is (4 bolt slayed outer holes,forged crank, forged rods with 7/16 bolts, and forged pistions) alum. heads(intake valves 2.25 exhaust 1.88- 110cc) , cam is .640/.598 lift- 114 degree lobe separation with 1.7 roller rockers. It will be street driven mostly. I want to run a twin turbo at 5-8 lbs of boost. Was thinking no intercooler but using water/alcohol injection if needed. It is fuel injected (has 38 lbs injectors but planning on going with 60lbs), I have dual walbro 340s in the gas tank and I plan on use a FAST setup. I would like to be in the 700-800 hp range. Redline is 6200 rpm and would like boost by 2500 rpm. It's backup up by a 200r4(well built) and 12 bolt rearend(373 gear) . Running 13in wide tire.

Thanks for any suggestions.

Chuck

Be careful on the exhaust side it is going to be very easy to choke that sized motor with the hp requirement.

[wilkinshc]

Originally Posted by John Wilde

Be careful on the exhaust side it is going to be very easy to choke that sized motor with the hp requirement.

Are you saying that small of turbos would hurt more then help?

Thanks
Chuck

[turbolou]

Originally Posted by wilkinshc

Hi,

What size turbos would you recommend? I have 454 with 10.2 compression, block is (4 bolt slayed outer holes,forged crank, forged rods with 7/16 bolts, and forged pistions) alum. heads(intake valves 2.25 exhaust 1.88- 110cc) , cam is .640/.598 lift- 114 degree lobe separation with 1.7 roller rockers. It will be street driven mostly. I want to run a twin turbo at 5-8 lbs of boost. Was thinking no intercooler but using water/alcohol injection if needed. It is fuel injected (has 38 lbs injectors but planning on going with 60lbs), I have dual walbro 340s in the gas tank and I plan on use a FAST setup. I would like to be in the 700-800 hp range. Redline is 6200 rpm and would like boost by 2500 rpm. It's backup up by a 200r4(well built) and 12 bolt rearend(373 gear) . Running 13in wide tire.

Thanks for any suggestions.

Chuck

You don't need turbo's to make that kind of H.P. with a a big block your combination is all wrong to do that..Sounds like you bought a crate motor intended to be run N A Forget the turbo's & run the engine as is & save yourself a lot of trouble & expense.

[wilkinshc]

Originally Posted by turbolou

You don't need turbo's to make that kind of H.P. with a a big block your combination is all wrong to do that..Sounds like you bought a crate motor intended to be run N A Forget the turbo's & run the engine as is & save yourself a lot of trouble & expense.

Turbolou,

Your right, it is a crate motor. I was thinking of spraying it for the other 200hp but I hate the thought of refilling the bottles. My thoughts were to turbo it and run low boost for a couple of years and then breaker back down and build it right for the boost. Then I would have the setup (headers, plumbing, and gremlin) all worked out. I realize compression and cam are not ideal for a turbo but I seen LS1 running boost with reasonable success with similiar compression and cams.

Thank for the comments
Chuck

[rking]

Hey Chuck,

Is this going on a certain aluminum block that my father and I got a chance to look at .

If so, then .

Anyhow, I am building a Twin Turbo LSx with ported L92s. At only 402 cubic inches, I am going to be running 2 GTQ72s with around a 1.00 on the exhaust side just to keep it from choking itself.

Now with a 454, to let it breathe you are going to have to run some pretty strong turbos, however, with your horsepower goals, you wont need any boost hardly, and thus be way out of the effeciency of that size of turbo.

Some may say its not feasible, and why do it.... But I understand the appeal and because its just so dang ....

I have never built a TT 454, so I'm not an expert. I guess you could look at Nelson Racing Engines, I know he has some TT 454's, but they are more in the 2000+ horsepower range.

Here's an idea and question for anyone, would he be able to try something like 2 GTQ70s with huge exhaust housings? I would believe that those, on only 5lbs of boost, would be around his goals, if they dont choke down the engine!

[wilkinshc]

Hi Cory,

You got it! I have been side tracked and not getting much done on the vette but the 63 impala is coming along pretty good. It should be into paint the end of the month. We hoping to take it to phoenix in November if things go well. The engine from the GN end up with a stroker kit, ta alum. heads ported , roller cam, and 6pack fogger kit. It's backed up by the 200r4 and a 9". Went with the air ride suspension, and wilwood brakes.

Here's a link for you:

65cpe's photos and albums on webshots

A for the vette, since I won't have her done till spring I thought I might spend a little more money on her. I would love a whipple supercharger but they are get hard to find for a BBC. I was thinking on 1.26 on the exhaust side.

Chuck

[turbolou]

Originally Posted by wilkinshc

Turbolou,

Your right, it is a crate motor. I was thinking of spraying it for the other 200hp but I hate the thought of refilling the bottles. My thoughts were to turbo it and run low boost for a couple of years and then breaker back down and build it right for the boost. Then I would have the setup (headers, plumbing, and gremlin) all worked out. I realize compression and cam are not ideal for a turbo but I seen LS1 running boost with reasonable success with similiar compression and cams.

Thank for the comments
Chuck

My impression is that you have not had a lot of turbo experience. So it's good to ask questions before planning a project. There are many other things to consider in what your wanting to do.My opinion is that Turbos work best & are more efficient with smaller engines. The import scene is a good example.The other problem is the weight biased on the front of the vehicle.Were you to do that, 600 lbs heavier in the front VS rear would not be good for traction & handling. Furthermore the fact that your car is injected & you intend to have programmable engine management gives you plenty to learn & that experience will be valuable. When you're finally ready to take the jump to turbo's or forced induction. What you're wanting to do isn't impossible but you better hit the lottery first.

[wilkinshc]

Originally Posted by turbolou

My impression is that you have not had a lot of turbo experience. So it's good to ask questions before planning a project. There are many other things to consider in what your wanting to do.My opinion is that Turbos work best & are more efficient with smaller engines. The import scene is a good example.The other problem is the weight biased on the front of the vehicle.Were you to do that, 600 lbs heavier in the front VS rear would not be good for traction & handling. Furthermore the fact that your car is injected & you intend to have programmable engine management gives you plenty to learn & that experience will be valuable. When you're finally ready to take the jump to turbo's or forced induction. What you're wanting to do isn't impossible but you better hit the lottery first.

Turbolou,

Actually I have been running turbos for years, my first turbo was a 1978 Kawasaki Z1R TC motorcycle (factory experiemental bike). In 1979 I had it down into the 8.90's which was fast back then. My first turbo car was a 1982 Camaro- 400 smallblock with a gale banks carb turbo setup, bordix alum heads, venolia blower pistons, and ran 10.9's but the plumbing was a nightmare. Took 2-3 hrs to change the plugs. In 86 I bought my 1st GN. I loved it. In Nebraska they had me in a M class with an index of 14.8 if I remember right. Everyone hated it, I could leave with no boost and still beat anyone by over a 1/2 second. Have owned 6 GN's, 1 Turbo Camaro, and 5 Z1RTC. The bikes started with 10:1 compression from the factory and ran 6-8lbs of boost on a carb. With alky injection I could run 12lb easily on pump gas. The bikes were a drawthrough system and carb. Actually had to run a fuel pump as it would run out of gas in 3rd gear. We ended up running blower pistions, welding the crank (pressed cranks), porting head, and other little tweaks. Dynoed 268hp at rear wheels.

I have been burning GN chips for local guys for years so I have an idea on engine mangement (alway can learn more).

As for weight, you are right. I have an all alum. engine and the turbos will be locate just above the pan and back next to the firewall.

I have wonder what the results could be with a single turbo running off one side of exhaust? Any thoughts?

Thanks
Chuck

[Dusty Bradford]

You can pull it off with that compression, C-16 and conservative timing. If you buy too large of a turbo and have to turn the boost way down it's gonna surge. I'd be scared of 10.2 with much boost at all on pump gas.

See if you can pick up a pair of 4 bolt turbo's in the 64-67mm range.

Rking...check on the L92 heads. A friend spoke with a well known LS1 shop in Texas a couple weeks back about an LSX block and L92 heads with a 91mm for a street car. They did not like the decks on the L92's and advised against them for boost.

[Louie L.]

One of the LSX websites had pics of a sectioned L92 head. Some parts of the decks are really thin. But they are a steal.Maybe with low boost it should work.

[rking]

Dusty and Louie,

I appreciate it. Yeah, I have been spending hours on LS1tech.com just reading over stuff for the past year or so. I have a 6.0 liter iron block, Lunati internals, but only the L92s as of now. The intention is to get everything together, plumbed, then switch to the LSX block and the LSX 6 bolt heads when they are released.

The block and internals have proven to be 1000+ RWHP capable, the heads however have been noted to have a thin deck for forced induction. The ET and AFR heads are much better suited with a thicker deck, but why spend the money on a 4 bolt head that can still result in pushed water and lifting, when the LSX head has finally been given a release date. I know that it will take me at least the winter to get everything done, and give the head time to released.

As for the L92s not being good for forced induction, probably, but if I get a chance, I am going to push them to see what they really can do, and give my report!

[turbolou]

Originally Posted by wilkinshc

Turbolou,

Actually I have been running turbos for years, my first turbo was a 1978 Kawasaki Z1R TC motorcycle (factory experiemental bike). In 1979 I had it down into the 8.90's which was fast back then. My first turbo car was a 1982 Camaro- 400 smallblock with a gale banks carb turbo setup, bordix alum heads, venolia blower pistons, and ran 10.9's but the plumbing was a nightmare. Took 2-3 hrs to change the plugs. In 86 I bought my 1st GN. I loved it. In Nebraska they had me in a M class with an index of 14.8 if I remember right. Everyone hated it, I could leave with no boost and still beat anyone by over a 1/2 second. Have owned 6 GN's, 1 Turbo Camaro, and 5 Z1RTC. The bikes started with 10:1 compression from the factory and ran 6-8lbs of boost on a carb. With alky injection I could run 12lb easily on pump gas. The bikes were a drawthrough system and carb. Actually had to run a fuel pump as it would run out of gas in 3rd gear. We ended up running blower pistions, welding the crank (pressed cranks), porting head, and other little tweaks. Dynoed 268hp at rear wheels.

I have been burning GN chips for local guys for years so I have an idea on engine mangement (alway can learn more).

As for weight, you are right. I have an all alum. engine and the turbos will be locate just above the pan and back next to the firewall.

I have wonder what the results could be with a single turbo running off one side of exhaust? Any thoughts?

Thanks
Chuck

Great! So I won't preach to the choir, I go back to 1973 with my first turbo experience & still learning.Thats the fun of it. It's possible to turbo anything including a lawn mower. But is it practical. Definitely dual turbos.You would have to use a very large single & it wouldn't spool as quick.

[Louie L.]

Im sure that the L92 heads will work well with forced induction. Its just that you are goona have to be sensible with the boost. I heard that the guys from Hardcore were using Yamabond on their head gaskets to help retention. Might be a little trick to use. But again if boost numbers are kept reasonnable you should not need all that glue either.

I have looked at the numbers for those ET heads . Those things are pretty awesome.

[JDEstill]

Chuck, looking at all the specs you listed in your first post, and running through the calculation that I detailed in this article on the Turbo Regal website:
Turbocharger Compressor Calculations
(link to the spreadsheet I use is down at the bottom, so you can go through the same math pretty easily)
I get a maximum air flow of about 40-42 lb/hr (for 1 of 2 turbos) and a pressure ratio of about 1.8. Looking through the Garrett catalog it looks like a pair of GT3076R's would suit you really well. That is assuming that you have enough restraint to keep the boost down under 10 psi. I also made some allowance for the fact that you live at altitude, and the possibility of water/alky injection.

I'm not sure what the equivalent turbo is in standard GN nomenclature; ie what that relates to in the TA/TE/GT sizes. Or in the Turbonetics sizes for that matter. But it shouldn't be too tough to figure that out.

I'd guess you would end up with around 700ish hp from that setup, plus or minus 50ish depending on the all the details. Looks like the 60 lb injectors will be perfectly matched for the setup you described.

Understand that none of this is to say that your plan is a good plan, it's just answering the question you initially asked - what size turbo for that setup. It's going to be a little different than what most guys have experience with, since you are looking at low boost. Seems like most guys are looking for the flow at 25+ psi, but you need the flow at something a lot less than that. That changes up the size turbo you need.

John

[ITSNOTAGN]

WHoa, thats a no-go on the gt3076. those things are VERY tiny. think stock GN size here. Of your trying to keep costs down, i would do dual 66-67mm with a p trim and 1.1 housings. those should spool up to 8-10psi by around 2500rpm, that would be a sick street car, with 700+ft/lbs from 2500 and up. but being an alum block, i would think you would want to spin it up to 6500-7000rpm right? if thats the case i would most certainly go with a set of 70gtq's with a .96 housing. this is really the perfect turbo for your goals, with spool by about 3000, and enough to push your motor to 1200hp easily. also with that big cam and good heads, i wouldnt be scared of running 5psi on it in the least. that should do 700hp sooo easy, and a good 750ft/lbs. Good luck and keep asking questions
Gary

[JDEstill]

I have to disagree. With what he stated - 6200 rpm, 454, 5-8 psi - a pair of GN stockish type turbos is exactly what he needs. Stock GN turbos fed 231 cid pretty well at stock boost levels. A pair should feed 2X that (ie 454 cid) well - especially at the low boost levels he's talking about. The conditions he listed call for about 1150 cfm or so of compressor capacity. A pair of 1200 cfm turbos like your recommendation is way too much. I would be very worried about it performing well down low. Now maybe the best answer is to jump up a size over that GT3076, but I wouldn't go too far out. Unless he wants to buy 'em once, and be prepared for the future when he does want to crank up the boost. That changes everything.

John