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gmc
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Discussion Starter · #1 · (Edited)
Thought I'd start a new thread ..

here is a link to my post on inliners

http://inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=50964&Main=5596#Post50964

With long tube headers, stock compression ratio (mine is lower than stock for turbo usage and rule of thumb is 5-10 hp per change in 1 point of compression so I lost 10-20HP by doing this), installing the cams in naturally aspirated e.g. with overlap and a bigger throttle body I'm confident that this engine would make 400HP easy. Just pulling the mufflers it gained 25 HP!. At WOT the engine was making 5" of vacuum ! so it was starving for air from 5300 to 6900 RPM. 5" is a lot. Its like running at 3/4 throttle.

So the performance increases came from:
a: porting the head
b: camshafts
 

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non_gmt360 other
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Congrats on the numbers.....your remark about uncorking the exhaust is funny because some time back, there was an arcticle online about the TB and IIRC, they mentioned that 'according to a GM engineer' (or someone), there was about 30hp locked up in the exhaust system. Good to know it's true....

Jeremy
 

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2007 chevy trailblazer_ls
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Great results. Not to discredit as this is a good sign of things possibly to come BUT you have to figure in no alternator or fan clutch on that thing. Im sure that gives you a GOOD boost in numbers.
 

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Discussion Starter · #9 · (Edited)
Alternator was installed no other way for the water pump to run without it. No mechanical fan nor will there be the permanent install. Lets say it makes up for the lower compression I'm running... Still its a solid 60HP more than a stock '2006 and 75 more than a stock early engine.
 

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Discussion Starter · #10 ·
N/M I just read the thread. :D

but wow those are huge spec numbers for your cams! Was there any increase or decrease in the gas mileage?
Don't know yet - the engine is still on the engine stand. Hard to compare what I get against a trailblazer since the engine is going into my '51 GMC.

Time will tell ...
 

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gmc
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Discussion Starter · #11 · (Edited)
so what do you suggest doing to the exhaust to get the extra ponies out? straight pipe it? cats out?
Once you have all the bolt on parts (cat back CAI etc...) - head work will get you power without giving anything else up e.g. drivability etc. Then add cams. For a true street engine I'd go smaller duration/lift than what I did and set them up for NA mode with overlap. I think a good head port/street cams + a good tune including the VVT table would be a good 40-50 HP with no other changes.

If your running an early engine with a plastic valve cover I'd say there is 30-40 HP in the head alone. The exhaust port is so restrictive its not funny.

I have a 2002 head here and it would be interesting to get it set up on a flow bench and see what the numbers are. Guess it would be about $150 to get it done. Having just paid for the dyno time I'm don't have the extra $$ to spare so if a few folks cared to gather up a collection I'd get the work done.
 

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2005 gmc envoy_sle_xuv
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Very nice, by porting do you just mean port matched to the gasket? I think this is a very large improvement to the community.

I just want to find the time to take the head off or buy a spare and do some work. With the new updated cams, does it give you any lopeyness with the duration?(I'm a sucker for it, even though I would probably tune it out)

Did you need the larger injectors or did you put those in for anticipation of the turbo?

Also for the throttle body being at 75, would the 90mm LS throttle body be too big and lose too much flow down low? Or what else do you know that would be suitable that is also drive by wire is the issue? Just found this >>>> ( http://cgi.ebay.com/ebaymotors/99-0...c0.m245&_trkparms=65:12|39:1|72:1171|240:1318 )

Ohhh I can't wait to get some round aluminium now
 

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gmc
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Discussion Starter · #14 ·
See mid body answers


Very nice, by porting do you just mean port matched to the gasket? I think this is a very large improvement to the community.

No the entire exhaust port from the valve seat through the bowl into the double runners then into the final port all need work. If you have not done any head porting before this isn't the head to learn on.

I could recommend an excellent shop if so requested and the cost is reasonable. Once the head is ported it would need a full valve job to blend the port work into the seat.


I just want to find the time to take the head off or buy a spare and do some work. With the new updated cams, does it give you any lopeyness with the duration?(I'm a sucker for it, even though I would probably tune it out)

With DOHC you can set up the amount of overlap and thus the lopeness - want more increase the overlap! Thats the really neat thing about this head (plus being 24 valve..).

Did you need the larger injectors or did you put those in for anticipation of the turbo? Mainly for the turbo.

Also for the throttle body being at 75, would the 90mm LS throttle body be too big and lose too much flow down low?

Without the cams and head work I don't think a bigger throttle body will make any difference.

Or what else do you know that would be suitable that is also drive by wire is the issue? Just found this >>>> ( http://cgi.ebay.com/ebaymotors/99-0...c0.m245&_trkparms=65:12|39:1|72:1171|240:1318 )

Ohhh I can't wait to get some round aluminium now
 

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2005 gmc envoy_sle_xuv
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Oh i definately won't attempt something like this as my first head, I have a local shop www.maldenmachine.com who do very good work which i will probably use.

I meant for the larger throttle body after i install the cams and port the exhaust out will it be necessary and how big would you recommend.

You seem to be 1 of of the 10 people here who actually know what they are talking about engine wise(and one of the few to throw money at this vehicle). I would love to FI this engine but if i can get this amount of power from cams and head work theres no need to really for a daily driver.

I just bought a CNC machine with a lathe, so machining blanks out of billet will not be an issue at all.

I am planning to install nitrous on this engine in the future as I am creating a product for everyone who want the extra power without doing major engine work.

Thanks for all the information!

oh and i wanted to ask i looked at your past thread about getting cam blanks you said you had them cut from 8620 round bar. How thick of a diameter piece did you get to make the blanks.
 

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gmc
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Discussion Starter · #16 ·
cam blanks-

I'm going to get set up on TV as a vendor and will be setting up a group buy for cam blanks within 2 weeks. I have design completed and ready to go.

Details to follow.
 

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Discussion Starter · #17 · (Edited)
I meant for the larger throttle body after i install the cams and port the exhaust out will it be necessary and how big would you recommend.
Most likely 90mm but the stock intake manifold is a problem, as the hole is the same size as the 75mm TB - so adding just a bigger TB isn't going to solve the problem. This will though...

http://profile.imageshack.us/user/efi_diy/images/detail/#507/pc070530uc8.jpg

The prototype is 80% complete. Its shown in the mock up stage without the TB mount.

Here are the runners in "as cast" condition before any machining was started.

http://profile.imageshack.us/user/efi_diy/images/detail/#24/1001002h.jpg
 

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2005 gmc envoy_sle_xuv
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Ahhh ok very well, when the time comes i mean for your application the intake manifold you are constructing is good for the boost. It looks like you got yourself into backyard foundry stuff. I applaude you because i would never deal with molten metal.

Since the intake manifold is made out of that crappy plastic stuff, ill probably just buy a spare, slice off the restricted end and fiberglassing something new on there for just a quick simple solution.
 

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Discussion Starter · #19 ·
intake

You might have a hard time to get it to stick. If I am correct the plastic has a low surface tension. Glues tend not to stick well.

I did try pouring metal last summer... then had the runners in the picture poured at a commercial foundry..

I am working on tooling that will allow the head flange, runners and plenum base to be cast as one part. The upper plenum and TB mount are fabricated.

End of summer on this one....
 
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