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Keep the bigport? 7age build

Posted: Sat Aug 11, 2018 2:24 am
by Max2503
I want to build a 7age, but have been given advice to dump my bigport head for another option. Is all lost with the bigport?

Re: Keep the bigport? 7age build

Posted: Sat Aug 11, 2018 7:49 am
by totta crolla
I guess it depends on who gave you the advice and if indeed you would take any advice offered here ?

Re: Keep the bigport? 7age build

Posted: Sat Aug 11, 2018 8:39 am
by jinx
I want to build a 7age, but have been given advice to dump my bigport head for another option. Is all lost with the bigport?

No. Only thing lost, is the one who gave u that advice.
From normally aspirated street to 500+hp, bigport been there done it
what is your goal ?

Re: Keep the bigport? 7age build

Posted: Sat Aug 11, 2018 10:35 am
by Max2503
I'm looking at around 160+, and I want to stay NA.

Re: Keep the bigport? 7age build

Posted: Sat Aug 11, 2018 4:41 pm
by jinx
search the crapload of 7AGE builds on the net. More than a few raved about their bigport 7A builds

I'd imagine you're after the torque increase.
Its CRITICAL u get cam timing in sync. Some fail = disappointing performance
I'd keep TVIS & intake (unless u got ITB plans).
Look into smallport pistons/final 7A comp ratio (compatible with your fuel)
carefully choose proven cams..... probably 7500rpm redline
tune with most basic megasquirt

Re: Keep the bigport? 7age build

Posted: Sat Aug 11, 2018 11:34 pm
by totta crolla
A lot depends on the induction system, I would think the TVIS bigport inlet would struggle a bit with cams, a longer stroke and 160hp
The smallport inlet would cope better and you could get away with shorter duration cams.

Re: Keep the bigport? 7age build

Posted: Sun Aug 12, 2018 2:22 am
by Max2503
I've got an aftermarket ecu running slivertop itbs. I had thought about smallport pistons. On cams, I was thinking of 272 both, or catcams 275/267 setup.

Re: Keep the bigport? 7age build

Posted: Sun Aug 12, 2018 5:19 am
by jinx
for a daily driver tvis could only enhance 7age torque.
Yeah, 160hp require fairly aggresive cams, that might leave the intake behind ? dunno
Vehicle use & hp goals would dictate intake - broad midrange tq, or peak hp
if screaming around with noisy ITBs, where the tach rearly see under 5000rpm = different scenario

160hp crank or wheel?
google 2sec; http://www.speed-industries.ch/wordpres ... e/?lang=en

like i said, really no need to guess at any of this. Too many examples out there

Re: Keep the bigport? 7age build

Posted: Sun Aug 12, 2018 10:08 am
by oldeskewltoy
First... the is no reason for you to ditch the largeport head, as you will be using ITBs. If you were retaining the stock manifold, it might be worthwhile to run a smallport to achieve your power goals


160hp... or 160whp? - - VERY important difference

ASSUMING the later..... 160whp

Max2503 wrote:I've got an aftermarket ecu running slivertop itbs. I had thought about smallport pistons. On cams, I was thinking of 272 both, or catcams 275/267 setup.



To run those cams(Cat cams listed) the head will perform a WHOLE lot better with port work, the 275 is 10mm of lift, so you MAY need to have the lifter buckets machined for the cam to physically turn.

As to the pistons... You could run either stock 4AGE piston, but why? You are building a performance engine, and unless you have something to prove, I'd look to get a better designed piston (with holes for the oil rings to evacuate oil instead of a slit).

2 things are VERY important with a 7AGE..... 1) as has been mentioned, cam timing. You can purchase a "broached" (re-cut) crankshaft timing pulley, or not - but it is always best to set cam timing AFTER you have confirmed TDC. 2) Set piston squish @ .032" (+ or - .002") - "Squish" is the gap between the top edge of the piston @ TDC, and the flat parts of the combustion chamber.

The crankshaft can likely survive 8500 rpm, the stock rods may.... or may not, I'd recommend MRP 7AGE rods.

--------------

If I were building your engine, I'd recommend big valves(32mm intake, 27.5mm exhaust), and instead of the Catcams 275/267, I'd recommend a set of the big lift(10.7mm) 268 cams. I'd run a custom piston, the crown would be -2cc volume, and MRP rods.

Re: Keep the bigport? 7age build

Posted: Sun Aug 12, 2018 1:25 pm
by Max2503
I like your recommendations for the build...any idea on suppliers for the cams and pistons?

Also, with this build, will I notice an improvement over a 4age with the same mods?

Re: Keep the bigport? 7age build

Posted: Sun Aug 12, 2018 5:26 pm
by oldeskewltoy
Max2503 wrote:I like your recommendations for the build...any idea on suppliers for the cams and pistons?

Also, with this build, will I notice an improvement over a 4age with the same mods?


I can get you the cams... the 268/10.7mm cams WILL REQUIRE machining the lifter buckets to rotate. The pistons should not be too big a deal.

If both engines have the same cams/compression, and the build quality is equal the 7AGE will make more power than a 4AGE.