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Discussion Starter #1
For a NA b18c1, are itr valvesprings and ti retainers enough for 9000 rpms?

if not, are itr valves required?

thanks in advance
 

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If that's all you're doing to your engine, then you are wasting your time. That extra 900 RPM is worthless unless you are still creating power...

I believe you need cams as well, but I may be wrong...
 

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people have added Portflow inner valvesprings to the ITR outers when they ran the Toda B cams and a 9k redline. I see where you are going with your line of rationale...the retainers can give you an extra 200-300 rpm and that gets you in the 8700-8800 rpm ballpark but does not prevent valve float (assuming stock cam lift, rocker arm ratio, installed height and therefore no coil bind issues). If you assume an 8600 rpm tolerance limit to the stock ITR springs you will be fine. I would not personally push it to 9k but I'm a chicken without a big budget. You may have bigger kahonas and inherited the million from your rich uncle who just died...

BTW I run on DPR competition grade valvesprings rated for 12mm valve lift/ coil bind and a 10K redline not ITR valvesprings.

Justin, I somehow doubt that he has stock cams.

here's Chris' (GZR4DR) GSR engine with ITR cams (and some tricks that I have been sworn to secrecy) to get 200 whp on a stock bottom end:



clearly you can see that the itr cams did not need more than an 8k redline to make 200 whp.
 

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ITR valves just saves you the valvetrain weight (12%) compared to the GSR valves...valvetrain mass wrt retainers, VTEC locking pins, rockers, and valves assist in achieving the higher redline but certainly does not prevent the downside... which are heat and piston slap from valvesprings and retainer which were not up to the task asked of them (coil binding, valve float, valve face and seat wear).
 

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Hmm, I'm hoping to achieve the same thing myself. 200whp on stock bottom end and cams. Definitely getting schooled on the ins and outs of engine tuning, someday maybe...
 

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Discussion Starter #6
Thanks for the replies..

Forgive me for being a skeptic, but that graph is kind of hard to swallow...
 

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More info on what he has in the car would help with believability. I don't doubt you, but it would help us trying to get there if you were allowed to ellaborate.
 

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Taken from the website for this '94 GS-R said:
Engine Mods, Prospeed Performance headwork, Type-R cams, AEM cam gears and CAI, JDM ITR 4-1 headers, full Type-R exhaust, Type-R intake manifold, Apex-i V-AFC, FPR and guage, Prospeed Mugen chipped ECU, lightened flywheel... Dyno tuned.
I say not bad for a stock bottom end GS-R. I must also say that the pictures of this car are excellent. Very beautiful JDM front end on a 4 door.
 

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As I said I won't be able to discuss how he got that level of power...somethings people worked hard for to get that edge and difference. Why would they want to give it away like a free prize in a Cracker Jack box to anyone? I think you would understand that. Needless to say the point is not whether you believe me or not. The point was that ITR cams CAN be made to achieve 200 whp with a fat midrange in the proper package and tuning. It's certainly not common though. The cams aren't holding you back from that level of power.
 

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Definitely I've seen a couple ITR cam setups make in the 200whp range. Esteban here in SoCal made over 200whp on ITR cams at Dynamic Autosports. Makes me rethink about even getting cams as I see numerous big cam setups not even hitting 200whp for whatever reason coupled with all the problems that go along with bigger cams.

Tuning and proper engine package just become so important when getting to the 180+ zone in N/A. If I can hit 200whp on my stock cams with a strong midrange torque curve like that I'll definitely be satisfied. I'm not hardcore enough and really don't have the funds to go for the 220whp+ all-motor mantra setup so I'm just going to push the B18C5 engine as far as it will go.
 

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Discussion Starter #12
prospeed? weren't those guys on MTV or something?

i don't question the cams...

what gets me is his setup with STOCK gsr bottom end.. and i assumed the 4-1 header is a mugen header as listed on the dyno sheet.

i have a pretty good idea as to how he did it, but still..

there are a number of ways to reach 200 whp.. imho, in the end the costs tend to end up around the same..
 

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if a gs-r bottom does not need high static compression.. what would happen if those prospeed guys say, threw in ITR pistons and bumped up the compression to 11.0:1, or even threw in a mugen head gasket? im assuming then that the power will not increase that much?
 

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Discussion Starter #15
viprtwo on Aug/28/02 said:
if a gs-r bottom does not need high static compression.. what would happen if those prospeed guys say, threw in ITR pistons and bumped up the compression to 11.0:1, or even threw in a mugen head gasket? im assuming then that the power will not increase that much?
they probably milled the head to get an increase in compression
 

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ToDa003 on Aug/29/02 said:
they probably milled the head to get an increase in compression
I was thinking that and/or a thinner headgasket. Overall it just sounds like an excellent porting job matched correctly to engine package.
 

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Discussion Starter #17
okay.. back on topic..

MD: Tell me what you think of this.. I move the gsr intake springs to the exhaust side, buy itr intake springs, and then add portflow inners to both my intake and exhuast side.. along with ti retainers, this shoudl be good for 9000 rpms..

thank you in advance
 

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Toda, the portflow valvetrain calls for ITR intake outers on BOTH SIDES. i would consider buying two sets of ITR outers and the full set of portflow inners.
MD: do you think this will be too stiff even for ITR cams at 8400 rpm? i understand there is no reason to use anythign but ITR springs. but i'm planning to upgrade in the future.

my main concern is valvetrain wear, and timing belt wear with the stiffer valvesprings
 

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Discussion Starter #20
Vipr2: ITR exhaust valve springs = GSR intake valve springs

if you're planning to rev to 8400 with itr cams, just get the ITR valvesprings and retainers. That is all you need.

stiffer valvesprings are not required in this case and you will also lose power with it.
 
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