GN1-R's, Ported & Unported stock heads.

Aluminum headed combo 2006:

Unfortunately, I haven't run the car too much with the GN1-R's because of AFR problems I was chasing down. I changed 3 things since those times above....the heads, the intake and the intercooler...all three are still on the car. I was still using the same 70 P trim turbo and ATR roller cam. The best run was a 6.69 at 104 with 25psi of boost with unstable AFR's. The car also weighed more... about 3580lb. So, I guess I can say that running 5psi less boost and the car weighing 130lbs more these changes helped.

Since the above aluminum headed times, I've a added a FAST XFI... which fixed my AFR problems and added a stroker crank and a 220-224 cam.



any new numbers for this combo ? how much the new heads, stroker crank and a 220-224 cam was worth ??
 
any new numbers for this combo ?


Nope, not with the stroker engine. It's still at the machine shop.

I wound up buying another roller cam instead of using the 224 ductile roller. It's now a billet roller with 226-226 duration and .580 lift.
 
Please note using the Gn-1 R heads require you to notch the cylinder bores on a 3.8 motor. I wonder if this is hurting you as you have a big valve on a small cylinder it may not flow that much over the regualr gn-1 on a 3.8. Just thought i would mention that before people starti buying them and run into problems
 
What needs to be done is for someone to step up and have different sets of full race ported heads (as delivered out of the box) and compare them all on a 3.800" bore engine. I'm sure there are people on here that actually KNOWS if the larger valve does hurt but don't step up with the plain facts and flow number sheets. :rolleyes:
 
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What needs to be done is for someone to step up and have different sets of full race ported heads (as delivered out of the box) and compare them all on a 3.800" bore engine. I'm sure there are people on here that actually KNOWS if the larger valve does hurt but don't step up with the plain facts and flow number sheets. :rolleyes:
My interest in this thread is that we a have an iron headed 3.8 on stock computer 70 non BB turbo 72# injectors using Eric marshals program developing about 720 H.P. 3600# with driver, stock gears, 6.39 109 mph.Basicly a hi 9's car. We need to become more competitive in our class. By changing to a programmable system & aluminum heads what do I hope to gain? I see cars out there playing hell to run that good with lighter weight & all the good stuff. I would hate to spend the money & go backwards.Point also is before throwing rocks at the stock combination I wanted to maximize it. I will for sure be trying a set of aluminum heads next because we have hit a pref. wall & Maybe will have the answer to that comparison question. At this stage it's important to do one thing at a time & not go over center. I hope Eric can come up with something that will allow us to continue with the stock computer. I also have my reservations about changeing that.But thats a topic for a later day.
 
IN order to run those numbers on iron heads , they must have been reworked quite a lot, how much effort have you put into them?
 
My interest in this thread is that we a have an iron headed 3.8 on stock computer 70 non BB turbo 72# injectors using Eric marshals program developing about 720 H.P. 3600# with driver, stock gears, 6.39 109 mph.Basicly a hi 9's car.

Now the magical question is what was the boost level and was that with a Q trim or a P trim turbo?
 
What needs to be done is for someone to step up and have different sets of full race ported heads (as delivered out of the box) and compare them all on a 3.800" bore engine. I'm sure there are people on here that actually KNOWS if the larger valve does hurt but don't step up with the plain facts and flow number sheets. :rolleyes:

Not exactly what your looking for, but I'll give my experence:

Mild (very mild) ported GN-1 heads
10.05 @ 134.1 mph at 28psi. DA ~2200ft

Max ported GN-1 heads
9.91 @136.4 mph at 26psi. DA ~ 3500ft

Intake was gasket matched only. Neither set had big valves.
 
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Not exactly what your looking for, but I'll give my experence:

Mild (very mild) ported GN-1 heads
10.05 @ 134.1 mph at 28psi. DA ~2200ft

Max ported GN-1 heads
9.91 @136.4 mph at 26psi. DA ~ 3500ft

Intake was gasket matched only. Neither set had big valves.
Those are some good numbers.I can remember in the early days trying to break into the 11's Now you get no respect unless your in the 9's with a stock block no less.
 
Those are some good numbers.I can remember in the early days trying to break into the 11's Now you get no respect unless your in the 9's with a stock block no less.

Thanks, getting into the nines took me awhile. Staying there is a matter of $$$.:p

What I would really like to see is TA vs. Champion (with or without big valves). I've seen flow #'s, but no back to back testing.
 
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Thanks, getting into the nines took me awhile. Staying there is a matter of $$$.:p

What I would really like to see is TA vs. Champion (with or without big valves). I've seen flow #'s, but no back to back testing.
Spoke to my Cly head porter today & we discussed advertised flow numbers.He has people coming in to get the claimed flow numbers verified & has had a 100% track record of the numbers being exaggerated.
 
Spoke to my Cly head porter today & we discussed advertised flow numbers.He has people coming in to get the claimed flow numbers verified & has had a 100% track record of the numbers being exaggerated.

What heads are you talking about here Lou ??? :confused: TA's or Champions ???
 
I found two pictures digging around on my computer. Again, this is to show people what these heads look like when installed on a 109 engine.

This 109 block has a .030 overbore. The red lines are where the top of the bore needs tapering. The valves do not hit the bore of the engine when opened.

GN1Rvalves.gif


GN1Rtaper.gif
 
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I found two pictures digging around on my computer. Again, this is to show people what these heads look like when installed on a 109 engine.

This 109 block has a .030 overbore. The red lines are where the top of the bore needs tapering. The valves do not hit the bore of the engine when opened.

GN1Rvalves.gif


GN1Rtaper.gif
I'm trying to visualize that, I assume your using a gasket as a pattern. Is there enough material to work with & have you been able to measure how much improvement if it's worth the effort
 
I'm no expert with highly sensitive electronics or flow machines to confirm that tapering the cylinder helps but I can judge by my common sense that it should flow better when there's no "wall" for incoming air to hit. Small bore Big Block Chevrolets also have this taper from the factory. Yes there is enough material to taper the top of the bore. I don't taper the entire top of the bore just where it's needed where the chambers overhang.

Here's a crude drawing to show what I'm talking about.

valvestaper.gif
 
Man just want to say thanx for the pics and this thread is good. Good info swapping here.
 
that make alot more since then the other picture. i agree it would only make sine that i would flow better due to it not hitting that lip and being a nice even curve
 
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