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View Full Version : Bigport REV limit..



--Redwork--
21st March 2009, 02:38 AM
Just wondering what the experts recon is a realistic rev limit for a worked bigport with standard bottom end.??

Currently set at 8000. But will be throwing in some big cams in the next few weeks witch will no doubt want the engine to spin a bit harder..

And what fails.? Is it the bearing or the rods.


Fairly new to 4a engines... And god there boggy down low. :(
So used to cruisin round at idle every where in my dunnydore.
But there still heella fun :thumbup:

Clinton
21st March 2009, 09:14 AM
standard rev limit is like 8500 or 8600 with a jap computer?. i wouldnt push it that much further with a standard bottom end. but hey. what do i know..

Jonny Rochester
21st March 2009, 09:28 AM
Clinton... what can I say.:oh:

--Redwork--
21st March 2009, 09:29 AM
This is a BIGPORT clinton... from what I understand AUS limit is 7500, JDM is 7750.

20v would have closer to what your suggesting Clinton...

Clinton
21st March 2009, 09:29 AM
did i say something stupid again? not even joking mine went to 8600. maybe my tacho is raped but?

--Redwork--
21st March 2009, 09:34 AM
Clinton... I dare say something was amiss... It takes an awfull lot of reving to get to 8600 with a standard bigport..

i don;t have a tacho on mine.. when I first got it running i thought it was reving its tits off untill my freind told me I'd only hit 6g. HAHA..

So I set the limit at 8000 then tried to hit it.... Takes a bit...

rthy
21st March 2009, 09:36 AM
havent got my jdm ecu over 7800, adm is about the same too

Jonny Rochester
21st March 2009, 09:43 AM
You can rev it to 8500 if you want, but obviosly that is over the stock ECU rev limit. I have heard several storys of failed conrods at 8500rpm. 8000 would be fairly safe.

slydar
21st March 2009, 09:55 AM
lol yes wrong again. hahahahahaha.

i wouldnt go past 8 man. and i doubt cams are gonna make it useful past there anyway. 8 is a lot.

slydar
21st March 2009, 09:58 AM
factory spec is 7750 for zenki. then though wound it back for kouki. most likely due to engine failures.

i intended to set my rev limit at 8000. my motor does have cams and also uses a 101 bottom end. there just no power up there.

Clinton
21st March 2009, 10:50 AM
i fale yet again...

Jonny Rochester
21st March 2009, 10:52 AM
Spelt f-a-i-l.

Konakid
21st March 2009, 10:58 AM
Hahahhaa

adam
21st March 2009, 11:04 AM
I've got ADM ECU powered bigport and it limits at about 7800rpms.

My motor's currently stock with just intake and extractors, it doesn't make any more power above ~6300rpms (according to my dyno graph) so my I've set my limit to 6500rpms.

sun_moon
21st March 2009, 11:05 AM
is it just me, or do bigports with stock cams feel crap after 6000rpm ?

Rice86
21st March 2009, 11:08 AM
my experince

adm ae86 with bigport with adm ecu, redlined at 6500, it wouldnt past that no matter what and it took ages to get to 6000 =.='

Jdm ae86 bigport, looks standard but dont know about internals, goes all the way to 8000 with no weird engine noise, but the gear box rattles like a fucker hahaha

sun_moon
21st March 2009, 11:10 AM
the bigport in my aw11 revs fine and easily to 7800, but just makes no power above 6k lol.

stock bigports are pretty shit IMHO..

yoshimitsu9
21st March 2009, 11:13 AM
is it just me, or do bigports with stock cams feel crap after 6000rpm ?

id agree there

also somtimes depending on fuel quality (even bp or mobil) it sounds like its pinging anywhere after 7000rpm

adam
21st March 2009, 11:13 AM
the bigport in my aw11 revs fine and easily to 7800, but just makes no power above 6k lol.

stock bigports are pretty shit IMHO..

Yeah, same with my motor. It'll rev to 7800 easily, but will be mostly noise after around 6k.

sun_moon
21st March 2009, 11:24 AM
lightly modded smallport in my trueno reved to 8 everyday and didnt flatten out like my aw11s bigport. then with some cams in the smallport it felt damn good.

i dont understand, bigport have longer duration cams, yet they seem shit at revving ?

--Redwork--
21st March 2009, 02:45 PM
Shit air speed with the crappy big ports and twin runner manifold...
And no compression.

sun_moon
21st March 2009, 06:39 PM
This Version Is Shit ! :P

compression is pathetic on bigports... i was very dissapointed after driving bigport engined car !

--Redwork--
21st March 2009, 06:49 PM
My bigport has only very slight head work around the valve throat and a valve job and I raised the compresion to around 10.6 and my friend recons it goes harder than his old small port engine..
And I still have cams to go in to.. :)

HAHA and yes This Version Is VERY Shit....
Tvis went in the bin... BUY BUY... nasty after thought of engineering...
It was ahead of its time in thinking but sadly, very poorly executed.. And unessesary

sun_moon
21st March 2009, 06:56 PM
TVIS causes so many problems ! i am always hearing of it staying open and staying closed !

filfilfil
22nd March 2009, 01:19 AM
Can anyone tell me if the stock GZE bottom end can take more safely (assume non factory ECU and cams etc...sorry to hijack!

Mr Fujiwara
23rd March 2009, 08:36 AM
well from what ive read, Bigports have a Cast Iron crank and the GZE (and Smallports?) and the 20vavles have a Steel cranks with beefier conrods to match, they would naturally be heavier due to much more material being there (toyota over engineering) for higher power outputs. BUT would easily be able to have a lot of material removed by a shop during balancing and have a lot of their mass removed, and could easily spin to insane revs.

in regards to standard bigports, ive got Twin webers on otherwise standard JDM bigport, ive got no TVIS and my power i would say is flat from around 3500 till 6000, i have no rev limit with carby setup and my needle has gone off the tacho before (when it used to drop gears, or when im furious) no power what so ever so thats over 8000 revs.
soon to build 7age with cams, forged goodies and bigport head and carbies, i'm curious to see if the 1.8 gets the airspeed up enough to make reasonable midrange.

lo_rolla
23rd March 2009, 09:56 PM
I'm amped to see what my limit will be.
Forged 11.8:1, 304* 11mm lift, oversize valves, H beams, modded crank and quads.... etc etc
The booklet that came with my Haltech says the haltech is good for 10500, should just run with that, eh?

The std big port in my trueno felt like it pulled all the way to 7750, but when I pulled it down it all appears to be std.

--Redwork--
23rd March 2009, 10:15 PM
My car hasn'y been tuned yet and is low as throw the mid range...
Only seems to START making power at about 4500 and easily revs to 8000rpm..
Hit limiter many times on our hills run the other day just trying to keep up casue my engine is soo sluggish when your in the next gear...
Compared to the car in front of me anyways...

Hopefully all cammed and tuned this Saturday...
Won't be a very impressive number though as the dyno reads very low compared to everyone else...
It seems like workshops all fudge the calibration on there dynos to read high so they can get more buisness.. My mates last dyno day nearly everyone who compeated complained that there car made heaps less power than usual..
Eg.. Another mates S14 made 350whp at the dyno day, but on the dyno at power cruise made almost 440 with only a few psi more boost... a couple a PSI doesn't make an extra 90 HP

slydar
23rd March 2009, 10:31 PM
most big ports feel shit cos theyre old and tired.

as mr red work has said, with fuck all work, his motor pulls quite well. big ports are inferior, but theyre not shit when theyre running right. they just hardly ever are.

PHA786
24th March 2009, 09:12 PM
Ow man. I've only got my smallport reving to 7000. I better increase that. Would i also set it to 8000rpm the same as a bigport?

sun_moon
24th March 2009, 11:13 PM
lol at only 7000 on the smallport !!! smallports make there power up higher than bigports, so please rev to 8000 :P

ke70dave
24th March 2009, 11:21 PM
i have a stocko bigport with a jap computer

i find that anything after 6500 doesnt really sound that great and doest seem to make much more power...

i know peak power is supposed to be 6500 or so, but it just sounds terrible reving any higher!

6000 is usually about as high as i go, this is just driving fast, not drifting. havent tried that yet!

Robo86
24th March 2009, 11:21 PM
bigports > life