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I came across flow numbers for a stock port cylinder head, it's actually incredible how the 4G63 ports just die around 9.0 to 10.0 mm of lift. A well-ported head carries into the 11.50 mm range pretty well, though: http://users.erols.com/srweiss/tablehdc.htm#MITSUBISHI
I had my choice on a great deal between the Jun 264s and Jun 272s and despite the age of the grinds, I trusted their machining more than any cam maker. Jun cams were the hottest cam in the world in 2005 (heck, the current FP Black record holder ran it with Jun 272s). The 272s are just huge and weren't the right choice, and I was fine with the 264's lower lift to get the velocity going at lower RPM to help the threshold boost response. I guess 0/0 and a kick-*** 4,000-6,000 range is the best I can hope for, but it should be a lot of fun while I'm losing those races.
For stock port flow figures on the intake side, this graph is easier to digest (my INT port is the blue line). Just for the sake of discussion, my Crane intake cam has an INT of 272 deg adv duration with 232 @ 0.050" (longer at 1mm), and 11.8mm lift. The exhaust side is 280 deg adv duration with 240 @ 0.50" (longer at 1mm) and 12.3mm lift. The ramp rates are at least as aggressive as the JUN 272, and the effective duration a little longer. On paper, this looks huge if we consider only effective duration. In actuality, this is a competition "rally" cam set intended for a ported head and small turbo with a 3500-4000 rpm torque peak and 6000 rpm limit.The difference is all in the cam timing, which of course is the point of this discussion.
Quote:
Originally Posted by Ted B For the standard Kelford 272 cam set, you can try retarding the exhaust cam by 2 degrees. That should help spool and midrange response, but I suspect that turbo setup will always have slow spool.
I asked again, sorry if I bother you. thank you for fast reply and help. approximately how much rpm do you think I can gain on spool to full boost?
It is difficult to answer this question. I do not have experience with that particular turbo setup, but part of the answer will determined by the tuning.
Intresting, thank you for the advice. Would a fully port and polished head with upgraded stock sized valves yield any additional advantages? I have a Curt Brown spec'd head.
If you have any recommendations in mind, would there be a specific cam you would recommend? I'm only really familiar with the GSC R2 cams and the S3's, but wasn't sure if the S3's would be overkill.
A very well ported head will flow well with stock sized valves. With the EVO head, the ports are the primary restriction, not the valve sizes. For street or short track use with your turbo size and open T3 manifold, I feel the GSC S2 is your best choice based upon power vs.spool characteristics.
For stock port flow figures on the intake side, this graph is easier to digest (my INT port is the blue line). Just for the sake of discussion, my Crane intake cam has an INT of 272 deg adv duration with 232 @ 0.050" (longer at 1mm), and 11.8mm lift. The exhaust side is 280 deg adv duration with 240 @ 0.50" (longer at 1mm) and 12.3mm lift. The ramp rates are at least as aggressive as the JUN 272, and the effective duration a little longer. On paper, this looks huge if we consider only effective duration. In actuality, this is a competition "rally" cam set intended for a ported head and small turbo with a 3500-4000 rpm torque peak and 6000 rpm limit.The difference is all in the cam timing, which of course is the point of this discussion.
Aside from the nominal (0.5mm) increase in lift, the standard Kelford 272 is a bit of a sidestep to the JUN 264 but perhaps with milder ramp rates. I'd try the cam timing adjustment with the JUNs before making a swap. If you wanted to make a change to Kelford, you might consider the 8-TX272R instead.
Here was some porting results I got from a long time ago.
Stock head. Ported Head. Ported Head with 1mm oversize valves.
1mm oversize with the ported head lost flow everywhere. The shop said the valve seats need to be replaced and the port shape changed to make use of the 1mm oversize (which follows what you said)
Ted, Thank you for contributing to this site/platform for so long. I thought about getting an adjustable gear and going back on the dyno. What setting would you recommend?
7.8:1 4g63 2.2 Built in 2007. 25K miles
Ported head/stock size valves
Super 99 with a .85 (backpressure is high but its snappy!)
Kelford 288 . Some Mivec advance at high rpm .
AMS intake
The Kelford 9-TX288 exhaust cam is ground on a 117 LC, which is reasonable given its lengthy 238 degree duration @ 1mm lift. I'm not sure it's worth getting an adjustable gear here if you don't already have one. If you did, I might try retarding the exhaust by 1 degree. The intake cam has very long effective duration at 242 degrees @ 1mm. Because the car has MIVEC, I would invest time in tuning MIVEC throughout the rpm range. The base position of the intake cam with MIVEC is 130 degrees, and I believe the range of advance for the MIVEC unit is 30 degrees. I suggest a MIVEC tuning curve that begins with the intake cam position around 112-114 BTDC, gradually advancing it to 105 from 3000-5000 rpm, and gradually retarding it to 110-112 by the power peak. You will have to play with this, but advancing the intake cam in the midrange tightens the LSA, increases overlap and gets best spool from the turbo, while laying off the advance and opening the LSA in upper rpm ranges maximizes efficiency and peak power.
@Ted B What are your thoughts on the following combo:
2.0 carillo rods and wiseco 10.5:1 and I have two sets of cams:
Comp 280 and GSC S3 non billet, and I have FP HTA3076r T3 .82 hotside.
Springs have been upgraded to Kiggly already and I am assembling the motor now but unsure of which cams to use.
I also have the AEM true time adjustable gears.
Also. stock unported head but its fresh if that matters.
I run a mix of e85 and 93, but mostly e85.
Any advice or recommend a better cam?
The GSC S3 is a good cam set, but not for your setup in my opinion. Your configuration will slow spooling as-is, and the S3 will only worsen that while likely not being able to make up for it upstairs due to limitations of the turbo. The S3 is a good setup for a ported head with large (e.g. 750+hp) turbo. The Comp Cams 280 is a good profile for an unported head and stock to medium-sized turbo. With your turbo, a -1/-1 setting will give you a good balance of focusing power in the rpm range that makes sense for the turbo without compromising in spool characteristics.
To address your last question, if you were to change turbos or go to a CNC ported head, I'd consider a GSC S2 or one of the more focused Kelford grinds. As-is, the turbine side configuration will be the weak link in the performance picture, not the cam set.
Thanks Ted. I will stick with the Comps for now then. Ideally, when the bank account is refreshed I'd like something in the 35r but not much more, this is a street car with occasional track use.
I bought these as GSC S2 but after checking the paint mark and numbers I have verified they are indeed S3.
As it was with this setup on a stock motor and cam gears set to 0/0 it made 429awho on a mustang dyno with 93. It is definitely laggy and I'd like to make it less laggy. I do have a new, on the shelf PTE 5857 with a .63 hotside as my back up. I can always toss that on in the mean time if itll help the cause
An HTA 3076R with large twinscroll T3 hotside is a good configuration. A local member had that with these same Comp 280 cams, and it was a ballsy setup. Unfortunately, unless something has changed, those housings were difficult to find, and the castings needed work to be suitable for performance duty. That same turbo with .63 A/R open T3 however offers all the lag of similarly configured billet compressor 35R, but makes less power. The .82 A/R T3 can only worsen the lag, and adjusting the cam timing to help will only lessen power up top. Just things to consider.
Im not opposed to removing this turbo by any means, its been in the car for 9 years lol. Do you have any inside details about the PTE 5857cea in a .63 5 bolt hotside?
I am somewhat limited unless I go to a whole new turbo setup and I am not quite ready. Maybe next year lol
Aug 10, 2022, 08:03 AM
