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twin turbo 350 v8 with 4-7 switch cam

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original balzer

original balzer

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This is for my 97 gmc but i figure its general since most people are running a v8. Anyhow i have a cousin named Rod(not realy sure how hes my cousin but family claims he is)that used to build all kinds of toys from sandrails to motorcycles.

He is very knowlageable with turbos as well. Today we got talking and i have done a little reasearch since then. On to the point-we was talking about twin turbos for a 350 v8 mainly my 97 vortec engine. Since it needs a new engine anyway i WAS thinking about GMPP's ZZ383 crate engine. But Rod has convinced me it may be just as cheap to build a twin turbo 350.

The build would be a basic rebuild to stock aside from a 4-7 cam swap, with a turbo friendly grind. Then useing 2 turbos originaly desinged for about 2.5-3.0l 4 cyl engines for the twin turbo set up. Figureing at about 8-10lbs boost this engine would be reliable and have in the neighborhood of 500-600 hp and should get GREAT economy with the 5 speed trans in the truck now.

After getting home i have done a fair amount of price hunting and resurch.
I have come to the conclution this could actualy be done resonably cheap, or at least around the same price as most any mid performance crate engine.

Furthermore I have done alot of thinking on the 4-7 swap cam and it can be done WITHOUT computer mods.

DISCUS

Balzer
 
The turbo parts are probably 3-4k.

You could go with GN turbos and save money.
 
The turbo parts are NOT 3-4k unless you buy them in some sort of kit.
basicaly the turbos (garret T3 or T4 would be ideal) can be had for $300-$400 if a guys willing to peruse e-bay for a while. The rest is headers, pipe, oil lines, and possibly a innercooler. An innercooler is spendy, but im sure the same goes for it on e-bay. There are affordable turbo header kits as well. The pipe for intake can be bent up by a muffler shop then painted. Oil lines can be custom made at napa and shouldnt run more than $30 each. A boost reactive feul pressure regulator-$60. Blow off valves are usualy part of the turbo. The silocone intake tube parts in various angles lenths and diamiters are cheap as well.

Balzer
 
Intercoolers aren't even that bad. I've been looking on evilbay and they're going from $100 on up depending on the size.
 
i like this vid of Chris Chow's GN better, although the dyno vid is pretty cool...


Rene
 
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Oh how I love the sound of twin turbo's at full spool. I have actually though of this option to get some good HP out of my 350, just don't want the clutter that the turbo's would add under the hood.
 
original balzer said:
Furthermore I have done alot of thinking on the 4-7 swap cam and it can be done WITHOUT computer mods.
Click to expand...
Wait a minute - forced induction without tuning? Or you talking about just the cam swap here?
 
Isn't the 4/7 cam an attempt to fix air/fuel distribution issues with a carb? As little benefit of a 4/7 cam as there is with a carbed setup, I'd imagine EFI would see even less, if any, benefit.
 
original balzer said:
The turbo parts are NOT 3-4k unless you buy them in some sort of kit.
basicaly the turbos (garret T3 or T4 would be ideal) can be had for $300-$400 if a guys willing to peruse e-bay for a while. The rest is headers, pipe, oil lines, and possibly a innercooler. An innercooler is spendy, but im sure the same goes for it on e-bay. There are affordable turbo header kits as well. The pipe for intake can be bent up by a muffler shop then painted. Oil lines can be custom made at napa and shouldnt run more than $30 each. A boost reactive feul pressure regulator-$60. Blow off valves are usualy part of the turbo. The silocone intake tube parts in various angles lenths and diamiters are cheap as well.

Balzer
Click to expand...
Good luck with the 300-400 dollar ebay turbos. I wouln't run anything from ebay that has to sping at 80,000 rpm.

Turbomustangs.com
 
dyeager535 said:
Isn't the 4/7 cam an attempt to fix air/fuel distribution issues with a carb? As little benefit of a 4/7 cam as there is with a carbed setup, I'd imagine EFI would see even less, if any, benefit.
Click to expand...

I kind of think it has something to do with the engine harmonics. I think the newer fords uses that firing order.

I believe you can get improved throttle reponse and 15-20 more hp.
 
The reason I think it's something other than 15-20hp is that if it were that simple to make that much more, the "old" firing order cams would be discontinued in 5 minutes.

As I recall in an article I read awhile back, you simply change the problem area by doing this, which is why the gains aren't really that great. I'll do some research, see if I can find anything other than a product hyping article. :)
 
http://www.holley.com/HolleyNews/article.asp?ID=37 3-12HP gain according to Lunati. I guarantee that is based on engine output, CID, etc., so wouldn't be an absolute in any case.

http://forums.corvetteforum.com/showpost.php?p=1559102013&postcount=6 6000RPM+? No thanks, not for a truck motor. :)

Really not much in absolute numbers from testing, so again, I doubt it's much other than to those who need every 1/10 of a second.

As an edit, I realize the new motors have a different firing order, (they are also solely EFI, different bore/stroke, intake routing has changed, cooling is different, and so on, all of which means you can't really compare just the different engine firing order) which is why I mentioned the "old" cams. It cost 0$ more to produce a cam with different lobe order, (if in mass production of course) and would become the norm for the first gen small block, except for racing classes where it's not allowed, if it were that superior. In any case, the 4/7 cam has been out for over 15 years, and is still not in the majority, and still costs more, so something doesn't add up.
 
dyeager535 said:
http://www.holley.com/HolleyNews/article.asp?ID=37 3-12HP gain according to Lunati. I guarantee that is based on engine output, CID, etc.

http://forums.corvetteforum.com/showpost.php?p=1559102013&postcount=6 6000RPM+? No thanks, not for a truck motor. :)

Really not much in absolute numbers from testing, so again, I doubt it's much other than to those who need every 1/10 of a second.
Click to expand...
Yeah I probably wouldn't bother on a truck. But I'm going to run one eventually in our race car. The fun starts at 6000 rpm plus :D

I can't see the corvetteforum link, I'm banned there :haha:

I think they make your motor sound different also.
 
daleearnhardt01 said:
Wonder why??? :rolleyes: :rolleyes: :rolleyes: :rolleyes:

I think you just make up stuff to make yourself look more knowledgeable
Click to expand...
What did I make up?

I was looking into building a 7-800 hp twin turbo for cheap and it just wouldn't work out so it didn't happen. There is a lot involved in getting the right turbo and stuff.

Since you know so much what do you think of these welds :rolleyes:

IMG_2046.jpg
 
He is right on one thing, however.

Stay away from those cheap chinese turbos from ebay.

You'd be better off spending 600-800 each for reman turbos from a reputable builder. Get one with an internal wastegate to save some money. Or buy one big honkin turbo and let it rip.

Also don't forget your 350 will have a not so boost friendly compression ratio of 9.6:1. So if you go with a rebuild you'll need to use some dished pistons to counteract the 64 cc vortec heads.
 
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