which turbo do I choose?

blackstallion12

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Dec 13, 2009
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Hey guys,

I have a 289 and I am kinda interested in turbocharging. I am fairly new to turbos but know basically how they operate. I have researched alot so far and I am only getting more and more confused with each forum site I open. There are so many different turbos, brands, types, models, ect and I cant keep up.

By the way... The engine right now is a good runner. I would say a conservative 325 horses. I think the compression is a good range for a mild to moderate turbo build. Im keeping my cam, heads intake ect.

I would like to setup twin turbos on my car... I would be very impressed with the high 300 hp range maybe 450? Nothing to burzurk. So, what would be good turbos to use? how much do they cost? What brand or where do I find them? I heard the turbos on ebay are garbage is this true? Which blowoff valves do I need? Do I need blowoff valves? Besides turbos, and some sort of blowoff valves, what other store bought items do I need?

I am planning on fabricating and plumming everything myself so a kit is not necessary.

Please dont get frustrated I really would like to understand this and I hope I am not irritating anyone with my ignorance!
 
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Hey guys,

I have a 289 and I am kinda interested in turbocharging. I am fairly new to turbos but know basically how they operate. I have researched alot so far and I am only getting more and more confused with each forum site I open. There are so many different turbos, brands, types, models, ect and I cant keep up.

By the way... The engine right now is a good runner. I would say a conservative 325 horses. I think the compression is a good range for a mild to moderate turbo build. Im keeping my cam, heads intake ect.

I would like to setup twin turbos on my car... I would be very impressed with the high 300 hp range maybe 450? Nothing to burzurk. So, what would be good turbos to use? how much do they cost? What brand or where do I find them? I heard the turbos on ebay are garbage is this true? Which blowoff valves do I need? Do I need blowoff valves? Besides turbos, and some sort of blowoff valves, what other store bought items do I need?

I am planning on fabricating and plumming everything myself so a kit is not necessary.

Please dont get frustrated I really would like to understand this and I hope I am not irritating anyone with my ignorance!



1.) You won't need twins for a low boost setup.
2.) Keeping your cam may be a bad idea, long duration= surging with a forced induction setup.
3.) Ebay turbos are junk, Precision makes nice turbos that aren't going to break the bank (~$600). Otherwise, a good used turbo should work.. but be careful. Tial makes nice blowoffs and wastegates, and I don't know if I would cheap out with either one. If either one fails, something is going to blow up.

You will need a blowthrough carb at the least, but they have a tendancy to be unreliable. There are nice ones out there, but they aren't cheap. Fuel injection is the way to go with a turbo and can be pulled of for about the same as a good blowthrough. An intercooler is always a good idea, they make more power and add a level of safety. More heat= more detonation. You will need oil lines from the block to the turbo and from the turbo to the oil pan, aluminum piping, silicone couplers, fittings,flanges etc. As far as sizing goes, there is alot of information out there. You need to figure out the airflow requirements of the engine at your desired power level.


Good general information:

TurboByGarrett.com - Turbo Tech101

The Turbo Forums.com


Turbo selection:
Turbo and Supercharger Maps

:flag: lol
 
For the purpose of this discussion, the number of turbos is irrelevant to the boost level. The choice of twins vs. single will come to either preference or packaging. Since twins are not technically necessary for packaging, it will be mostly preference.

The Turbo Forums.com has a whole forum dedicated to blow-through carburation with information on converting a Holley 4150 and tuning.

Regarding the cam, duration isn't the problem; lots of overlap is....well, unless you can manage a 1:1 turbo drive ratio.
 
For the purpose of this discussion, the number of turbos is irrelevant to the boost level. The choice of twins vs. single will come to either preference or packaging. Since twins are not technically necessary for packaging, it will be mostly preference.

The Turbo Forums.com has a whole forum dedicated to blow-through carburation with information on converting a Holley 4150 and tuning.

Regarding the cam, duration isn't the problem; lots of overlap is....well, unless you can manage a 1:1 turbo drive ratio.

Yeah, I don't really believe that twins will do anything better than singles.. You either have 8 cyl spooling 1 big turbine wheel or 2 banks of 4 cyl's spooling 2 smaller turbine wheels. I would imagine twins being less efficent, as there are less pulses per turbo and more rotational mass between the 2 turbine wheels. But I've been told different things and never personally compared the 2 in real life so I guess I wouldn't really know...

Everyone I know that used a blow through had problems. That doesn't mean they don't work, it just means that the people I know seem to have a harder time with them than with FI. I feel like all the negative attitudes towards turbos came from the times before modern fuel injection where carbs where the only option. Fuel injection just allows for smoother driving, higher efficiency and alot of adjustability down the road.

You are right, overlap will make a forced induction engine run poor.. But you know what I mean lol, higher duration usually means more overlap. The problem will occur when the exhaust pressure exceeds the intake pressure during overlap.

BTW Shelby, I'm not correcting you or trying to be a dick.. just trying to add more useful info to the discussion lol.
 
Carbs with low boost are not too hard. You do have to understand what makes a carb tick to make them work though. Innovate web site has some very smart people to help with blow through too. My carb works great and is all home modded.
 
To the OP:

It does sound like you need to do some reading on theturboforums

I would be very impressed with the high 300 hp range maybe 450?

you could do that on a bone stock 5.0 with a turbo kit easy

So, what would be good turbos to use? how much do they cost?

like stated, the most common setup is two thunderbird turbo coupe turbos.

Price is anywhere from $80-200 depending on the shape.

The best junkyard singles are Holsets.

I heard the turbos on ebay are garbage is this true?

theres actually a big thread on theturboforums about this topic. Its still a chance and you have to go through them regardless to check for chips/tolerances but the quality control is miles better than it was several years ago.

Which blowoff valves do I need? Do I need blowoff valves? Besides turbos, and some sort of blowoff valves, what other store bought items do I need?

Yes you need a blowoff valve (BOV). I think the ebay $40 junk is fine. Remove the inner spring and run it. The bov isn't as demanding as the wastegate which is what leaks off exhaust pressure.

Wastegates range from $80 for ebay stuff to $600+ tial stuff.

You can run the ebay-gates so long as you go through them. YOU (the end user) has to be the quality control when it comes to everything on there . . .

I had way under $1,000 in my whole turbo kit with a $80 Holset H1E, ebay BOV and wastegate and it made 505rwhp and 559rwtq on a stock 5.0, f-cam, weiand x-celerator and a home converted holley 650 on 93.
 
Its still a chance and you have to go through them regardless to check for chips/tolerances but the quality control is miles better than it was several years ago.

IMO, that is what makes it cheaper and easier to just get a good turbo in the first place. Having a shop go through a new eBay turbo is going to add another $100-200+ to the purchase price plus the time and trouble of taking/sending it in.

Your H1E setup is an example of how tough Holsets can be. It had fallen off the map long before 505rwhp. :eek: I don't know about H1Es, but HX40s are known for losing a turbine wheel once in a while. It seems to happen mostly with high boost diesels, though.

The trick is finding a Holset single that is actually sized properly for a gas V8 application. Most have huge turbines for the diesels they were designed to go on and the new ones have electronically-controlled(via proprietary protocol) variable geometry turbines. A pair of HX35s or HE351s would be pretty knarly on an SBF, though....and easily enough turbo for 600+bhp, no sweat. For 400rwhp, I don't think they would even know they were working. :rlaugh:

A pair of .60/.63 Garrett T3s are still nearly ideal for a 400bhp smallblock.
 
I don't think I would go to the trouble of a turbo for 400hp. A guy on one of my local boards has been high 6's with a stock 5.0 shrt block with heads cam and VicJr carb intake. He also went 6.30's with a 150 shot.
 
It had fallen off the map long before 505rwhp.

huh? The compressor map out there for the H1E is literally almost the same as a 62-1.

Most have huge turbines for the diesels they were designed to go on

the 21cm^2 ended up being right at a .96 a/r . . .

I am building a 466 with a Holset ht60 and it has a 98mm exhaust exducer and comes out to a 1.32 a/r . . .

granted some are big, but the holsets for some reason tend to be sized for some very common gas v8 engines.
 
1.) huh? The compressor map out there for the H1E is literally almost the same as a 62-1.

2.) the 21cm^2 ended up being right at a .96 a/r . . .

I am building a 466 with a Holset ht60 and it has a 98mm exhaust exducer and comes out to a 1.32 a/r . . .

granted some are big, but the holsets for some reason tend to be sized for some very common gas v8 engines.

The H1E is predecessor to the newer and more efficient HX40. While I don't have any H1E maps, I do have HX40 maps for the six-, seven-, and eight-blade varieties. Even the widest map compressor falls off the map around 55lb/min. That translates into ~500bhp worth of flow.

How were the CM^2 to area:radius ratio conversions done?
 
That translates into ~500bhp worth of flow.

all I can tell you is that on 14lbs with a H1E off a backhoe, 120k mile stock 5.0 shortblock, home ported e7s, weiand x-celerator, f-cam, t5, 1 5/8" shorty hedmans and a 3.5" downpipe it made 505rwhp at 5700 and 550rwtq at 3600.

I never took off the final dyno sheet but heres the one I used to set up a few grudge races:

dyno1fs7.jpg


it was like the 3rd pull we made on it and you can tell it was a long way from being tuned right. We ended up making probably 7-8 pulls after this one . . .

so whatever calculations you need to do to make that work . . . I am just telling you what I did. :shrug:

How were the CM^2 to area:radius ratio conversions done?

guy on theturboforums used some type of foam.