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My Twin Turbo 6.5 (GM4 & GM8)

The HX is just a bit slower then a GM8 get up and go wise. The twins are very slow compared to the HX. I wouldent recommend the twin set up I have for towning or racing. Works great for a commuter/highway truck runin empty though.
 
I was told his turbos were smaller then the GMX. I'm not exactly sure what kind. He also has custom headers for each one. I could see a significant gain in over all peformance compared to using the stock ones like I have. But building headers is alot of work.
 
tanman_2006 said:
Did Heath use twin GMx on his truck? I know he has a bit different set up and quite abit more extreme.
Click to expand...

Doesn't look like it:

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any updates? have you had it apart to see if the cracks are getting any more stress? has this convinced or detoured you to build the race engine? i run on the street empty at highway speeds and am interested in this. how much time/money did it set you back?
 
I haven't had to have to take it apart it still runs and drives as good as the day I finnished the build. It smokes more now Under WOT but I think it's cause the exhaust clamp is a bit
Loose going into the turbo. The build cost me about a grand and alot more hours were put into it then what I wanted. Olny cause u gotta figure it out as u build it. And I already built my race engine for my other truck. I really like my 6.5s lol
 
Hi DZZ71,(Is this your Year of Birth...)



Have I seen it properly...10 Seconds from 0 to 95 km/h...?


What have you used for Cylinder Head Gaskets..?


And what do you have for an Oil Pressure..?


Best regards...
Gunar
 
To get 1000km to a tank I gotta drive it very nice around 80-90 km/h on highway and not go over 2000 rpm in town. I have average oil pressure and no thats not my birthdate. It's January 5th of 1989. I used stock felpro head gaskets
 
22 Years old...and then so much on a Motor built...Hat down!..(its a German Proverb..)


1000 Km with one FuelTank :thumbsup:...o.k.-by this speed....:D


Gunar
 
Quick question here. If we want more volume of air vs. pressure, would the ATT possibly not be the best option for use as twins? Not sure on this one. Then again, maybe two ATT's would in fact be the best. I'm wondering if two smaller hx turbos would be closer to what Bill (Heath) did.
 
sshewins said:
Quick question here. If we want more volume of air vs. pressure, would the ATT possibly not be the best option for use as twins? Not sure on this one. Then again, maybe two ATT's would in fact be the best. I'm wondering if two smaller hx turbos would be closer to what Bill (Heath) did.
Click to expand...

Bill's are custom.

No way of knowing what's "close" unless you call the man and ask....
 
The ATT would to large to be used as twins with one on each exhaust bank.

If you are interested I may have something for you though in the very near future to run as twins. ALSO have something new coming out for the factory exhaust and kitty. wont need to replace the factory exhaust to use this turbo.
 
Had this conversation before, but the engine itself is a fixed volume. The flow at any given boost value is the same. The only way to change anything is in terms of mass, and if you lower the air temperature, then flow you do have would be more dense Then you would get more flow through the turbo itself, but the engine is still only a fixed air pump as far as volume goes. The main advantage of the twin for flow though, is its not as restrictive as running both banks into one manifold. So the twins are less restrictive and makes the truck more efficient.

Two GMx turbos, each at ~10cm^2 turbine housings, is about 20cm^2 worth of turbo. The 6.5 cannot drive much more than that. If anything, a couple 9cm^2 HX35s might work alright if quick spool is a concern, otherwise a couple of the newer 12cm^2 HX35s or similar sized turbo might be better for efficiency. I think Heath's turbos were small.
 
Thats more what I am thinking^^^. Giving me more ideas! I have a ton of room on one project truck....and making headers is very doable for me. I build the ones for my race cars. HHHMMMMMM! Ole brain is workin now!
 
U should try it! I would be interested to see the difference with smaller turbos and highflow headers.
 
Gonna go look at my truck today and see how much room I have where the exhaust ports meet the top of frame rail. The chassis is 87. Truck is 69! Only problem I see so far is flanges at the head. Anyone know where to find them? Oh wait! LiGHT BULB! Local school has cnc plasma cutter I have access to! HMMMMMM!
 
Another potential issue that I could foresee would be steering shaft clearance. It would be a trade off to either keep the stock shaft in place, or have to some real fancy fabricating to keep the runners the same length on each side off the engine. Hold on a sec, if each turbo is independent, would we necessarily need each side to be the same lengths? I mean other than for aesthetics and have it look similar to Heath's creation. Function over form.
 
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