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2G gsc s1 or Kelford 272

GSC S1 or Kelford 272?

  • GSC S1

    Votes: 4 33.3%
  • Kelford 272

    Votes: 8 66.7%

  • Total voters
    12

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LumpyVR4

Supporting Member
91
49
May 21, 2014
Sydney, Australia
Question is about my VR4, but I've put it under 2g because of the engine. I can't decide on cams. I've read a ton about both of them, but I keep changing my mind on which to get. The choices are GSC S1 or Kelford 272.

The engine they are going in is as follows
6 bolt 94mm stroker, 8.6 comp (I'm planning on E85 but it's not available everywhere), BC H-beams +625 bolts. Manley HD pistons, CNC ported 2g head with +1 valves, 80lbs beehives, Ti retainers, evo 3 intake.
Due to budget initially exhaust is ported evo 3 mani, ported evo 3 turbine with 20g compressor, 3" dump to 3" RalliArt exhaust.
Once money allows (at least a year) I'm planning on a small runner divided T3 manifold to a 56mm comp HX35 with 12cm twin scroll turbine running 30 psi on E85. I might get a JMF Street manifold at this point too.

Car is for highway and caning in mountains, but will see some traffic.

With the hx35, the 272s are a no brainer. I guess I'm worried about over camming while I still have the TD05 and end up hating it, or should I not worry because either way it's going to be better than my worn out stock engine that has 7 inches vacuum at idle, LOL.

Thoughts
 
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The GSC S1 and the Kelford TX272 aren't really comparable - the TX272 is a BIG cam. The GSC S2 is very close to the TX272, however. On the big cam test floating around, the GSC S2 was arguably the best all-around cam for the 500-550whp zone, beating out the TX272 in most data points. For your current setup, GSC S1. For your future setup, GSC S2.
 
Daren, Kelford 272s and GSC2's are both going to not have very good vacuum at idle either, just FYI.
The GSC1's will be good for now, but if it were me, I would do the bigger cams and not have to do it again, if you are looking for performance gains. You may run out of turbo before you get the most out of the cams, but they should still respond well. Someone please correct me if I am wrong.
 
To throw something else into the mix, I forgot to mention cam gears so I can fiddle with event timing.

Another thing to consider is redline. I'm thinking a hard limit of 8500 with the extra stroke and loss of rod ratio?
It's a street engine I don't want to rebuild evey 20,000, so TX272s might not be worth the bottom end loss with that top limit. The valve springs I have will probably start to reach there limits at 8k too, if not sooner. I selected them with the S1s in mind, but have started having delusions of grandeur.

@1990TSIAWDTALON did not realize the HX35 might not be enough turbo for a 272.

At the moment though I'm thinking the S1s because when I imagine my favorite bits of driving it's being at 5k through a long sweeper heading up a mountain and feeling the torque push me into the seat as I mat the throttle on the exit. But now I just thought about when the engine gets on the cams as it screams to redline. Dammit. Oh well, still got some time to choose.
 
For reference, the GSC S2 would probably be making the most power at 5,000 out of your 3 choices. They also make more power than the stock cams at 4,500. Having bigger cams also brings down static compression, typically allowing more boost on the same octane of fuel. Again, see the DSport cam test (2.0L with FP 3586R). I would actually prefer a cam setup that mitigates the torque spike around 3,500-4,000 on a stroker with a twin scroll HX35. Your transmission will thank you.

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My son is running a 7 bolt, HX35, BC280's at 35 psi to 8k+. It doesn't seem to run out of power. 11.50's off the trailer and then the track closed down for the winter, (and that was on STOCK cams). He hasn't been back but will be REAL soon. Just for reference to @Daren Eichmann 's comment on running out of turbo from true life experiences. :thumb:
 
My time slip says 13.5 @ 108 :)
Thats what the slip says, but my locals don't believe that. :sneaky:
I don't know why......:idontknow:
I am hoping to be able to update that soon Vegas! :thumb:
 
I was thinking that I would get S1s then move to S2s with the HX35 and hope I could sell the S1s. But I've had a different idea. Get the HX35G now as well as a BEP housing. I'll have to wait a little longer to complete the build, but I can wait. Once I've recovered from the main build cost I'll get the twin scroll manifold and sell the BEP housing.

Edit: Expenses I didn't think of when posting this are I'm going to have to get a custom radiator that sits under the support for extra space in front of the engine, and a new intercooler setup. I think I'm back to plan A of going with the S1s. The HX35 $1100, manifold $1800, wastegate $440, BOV $200, radiator $500, and intercooler $1000 is going to take a little while to come up with the cash to do. The only thing I don't like about Australia is how much parts cost due to shipping and exchange rates.
 
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Lotta money. What's the difference in the price of the 2 different sets of cams since you are already there?
Remember what you can replace as bolt ons and what you have to get into the motor for.
I'd get the insides done so I wouldn't have to do open heart surgery anytime soon. Just a thought.
 
Best I've found on cams are around $930 AUD a set delivered. Doesn't matter which ones. Maybe the better idea is to get the tx272 or S2 and adjust the valve timing to suit the turbo. An 8.6-ish 94mm stroker with a ported 2g head, even with the bigger cams, will probably perform better down low than my old 7.8:1 big port 2.0L anyway.

Not sure if this would help or hurt spool. Below is lifted from the Horsepower Heads website. They have the 2g head I'm using at the moment.
"On a 600 hp 4G63 engine, we gain 100+ HP from modifying the head (on the same boost as prior and provided the turbo has enough capacity in it)"
They have told me the port size isn't changed at the gasket face, so I guess it mostly bowl work.
 
I was thinking that I would get S1s then move to S2s with the HX35 and hope I could sell the S1s. But I've had a different idea. Get the HX35G now as well as a BEP housing. I'll have to wait a little longer to complete the build, but I can wait. Once I've recovered from the main build cost I'll get the twin scroll manifold and sell the BEP housing.

Edit: Expenses I didn't think of when posting this are I'm going to have to get a custom radiator that sits under the support for extra space in front of the engine, and a new intercooler setup. I think I'm back to plan A of going with the S1s. The HX35 $1100, manifold $1800, wastegate $440, BOV $200, radiator $500, and intercooler $1000 is going to take a little while to come up with the cash to do. The only thing I don't like about Australia is how much parts cost due to shipping and exchange rates.
Alot of people dont realize the true expense of things until you actually start messing around trying to install them and find out how many other things are affected by what you wanting to do!
 
FWIW, this came from EvolutionM, it may be of interest to you. A properly ported head will gain power everywhere.


"Here are my results before/after with Curt Brown port job and GSC S2 cams. No other changes were made."

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I would definitely want bigger cams for the stroker in any case. And what kind of space-age HX35 costs $1100 AUD landed? I'd estimate you could get one for half that, saving you money for the manifold. Seriously, look into the Mr. Peepers setup that Morrisson Fab sells. Get yourself an HX35 for $550ish AUD landed, the Peepers manifold with one wastegate, downpipe, etc and it should clear the radiator no problem. Heck, you could get yourself a T25 EFR 7163 that bolts onto a stock manifold for less than what you're trying to do. Comes with integrated wastegate and BOV, should clear the radiator. You would just need a downpipe fabricated.
 
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Kelford 272s and the GSC2s are great cams regardless of that chart!! Everyone will post different results . That card is not the HP gospel. Keltalon has proved that and he has BC 272s and makes over 700plus whp so everything depends on ones tune and setup.
 
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I would definitely want bigger cams for the stroker in any case. And what kind of space-age HX35 costs $1100 AUD landed? I'd estimate you could get one for half that, saving you money for the manifold. Seriously, look into the Mr. Peepers setup that Morrisson Fab sells. Get yourself an HX35 for $550ish AUD landed, the Peepers manifold with one wastegate, downpipe, etc and it should clear the radiator no problem. Heck, you could get yourself a T25 EFR 7163 that bolts onto a stock manifold for less than what you're trying to do. Comes with integrated wastegate and BOV, should clear the radiator. You would just need a downpipe fabricated.

This is the turbo I was looking at
https://www.ebay.com.au/itm/NEW-OEM...236056&hash=item2855e88ceb:g:w5kAAOSw-btaup6C
and this manifold
http://morrisonfabrications.com/product/dsm-twin-scroll-t3/
at current exchange rate it's $1781 + shipping
My problem with space isn't the radiator, it's that the fan lines up with the comp housing and I want to keep my AC so I can't put the fan in front of the radiator. It gets toasty here in summer.
I've actually considered the 7163 but went back to the HX35 because they are $1400 AUD cheaper. (all based on the best prices I could find online)
 
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