I have a JDM h22 block with P13 ecu. The valves were bent on the jdm h22 head so I am replacing it with an 5th Gen USDM h22 head.

My questions is will my JDM block & ECU/USDM head combination still allow me to redline the motor at 7400 SAFELY? I've tried the search but I did not find any concrete answers.

Is there a difference between the usdm and jdm heads? Or is it just with the ecu that's allowing the higher redline?

 

same exact thing so dont worry about the redline,

 

Short and sweet, thank you.

 

You can rev it to 8k no problem!

 

eeewwww......8k??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93b16hatch &raquo;</TD></TR><TR><TD CLASS="quote">You can rev it to 8k no problem! </TD></TR></TABLE>

there are quite a few problems, first off the ecu wont let u, secondly the valvetrain will bitch slap u, and thirdly it doesnt make power that high so its useless to do so

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by twistedbydezign &raquo;</TD></TR><TR><TD CLASS="quote">there are quite a few problems, first off the ecu wont let u, secondly the valvetrain will bitch slap u, and thirdly it doesnt make power that high so its useless to do so</TD></TR></TABLE>

Lol

 

Ummmm,

Not sure on this, but are the closed deck and open deck heads the same?

 

P13 will not let you go to 8k?

i have a 95 prelude vtec and going to 8k is not a problem

and making power is not why you take it to 8k, it's to stay in vtec after the shift

 

Good question! I hope they are the same, if they're not, I'm kinda screwed. Can someone shine some light on this?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Silver Surfer &raquo;</TD></TR><TR><TD CLASS="quote">P13 will not let you go to 8k?

i have a 95 prelude vtec and going to 8k is not a problem

and making power is not why you take it to 8k, it's to stay in vtec after the shift</TD></TR></TABLE>

if u are revving to 8k you either have a modified ecu or your tach is off, fuel cut is at 7600rpm on a normal p13 ecu, u would only have to rev to 8k on the 1-2 shift, shifting at 7200 wont leave u that far out of vtec that the difference is negligible plus shifting 800rpm sooner is doing a lot to keep your valvetrain happy, if u are revving to 8k due to a chipped ecu and have stock valvetrain ur asking for trouble

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bb_one &raquo;</TD></TR><TR><TD CLASS="quote">Good question! I hope they are the same, if they're not, I'm kinda screwed. Can someone shine some light on this?</TD></TR></TABLE>

I don't know . . . but I would think that the only difference *may* be with the cooling passages. If your engine is still appart you can just make sure the coolant passages in the head line up with the coolant passages in the block.

The main factor limiting the stock H22 redline to 7600 is valve float. USDM or JDM neither valvetrain can handle much more than that without floating. So unless you are upgrading your valvetrain I would stick w/ the stock 7600.

 

Thanks for the reply. I will look at the cooling passages on the head and block and report back to you guys when the head gets here.

 

also 8K on the tach is not TRUE 8K. Its also pointless as you make no power and are just at risk of causing further damage.

I ran a P13 JUN head on my USDM bottom end no prob.

 

I run my car to 7600 all day and it runs fine I can make it run to 8k it will still run fine.

I think it just depends on how often you get up there.
As far as staying on VTEC.....You can stay on VTEC from 1-2...you just have to know how to shift

 

if you actually rev to 8k on a stock head often you WILL eventually float a valve, most of you that are reving to "8k" are reading the stock tach, which is known for its incredible accuracy, so thats why you haven't bent valves yet,

as far as opendeck and closed deck heads, they are interchangable as well, differnt casting numbers and slightly different internals but swappable either way non the less

 

i took mines pass 9500 (VAFC) on my h22a due to a messed up tranny leading to a miss shift. stock head with type S cams. i dynoed my car, and it makes power till around 8200. i wouldnt recomend it but, whatever floats your boat.

still runs like a champ

 

I've got one of these insane test computers and have noted that both the speedometer and the tachometer are off by a significant amount. (Especially, in the upper ranges...)

So, if you fuel cutoff hasn't engaged, you haven't been hitting 7400 RPMs, even if you think you are.

Also, while the heads are the same in the cam timing area, it's my understanding that the JDM heads have multiple springs for the valves, where as the USDM heads have single springs.

In therory, this would make the JDM valve train a little more durable and stable at higher RPM's... How much is probably not super significant as most people do not do the daily VTEC thing...

Gerhard

 

why would they set a fuel cut off before redline at 7500
have you driven a 4th gen vtec?
sure the tach might be off but it seems that you should be able to take it to quoted redline and slightly past before bouncing off the rev limiter

 

YES! I noticed that my bad head had dual valve springs. I was confused thinking that all h22 heads had dual valve springs or whoever I bought the motor from had them re-done. That cleared things up!

 

all h22s have dual psrings

 

Well, I feel like an idiot now....

 

You guys are right about stock tachs being off, but arn't they usually slow and not fast? Meaning if your engine is at 7500 RPM your tach would be reading lower than that. That's how my ZC was; the fuel would cutoff before the tach ever read the right RPM.

My H22 and the one my buddy has both cutoff at 8200. So if factory fuel cutoff is at 7600 both our tachs would have to be off by 600 RPM. Which isn't that much I guess, except that VTEC comes on right when the stock tach reads 5200, which is correct right?

And about racing: You do need to go a little higher than you are making power to keep yourself in the powerband when you upshift. My engine puts down 180 to the wheels at 68-6900 RPM, at 7400 that has dropped to like 165 but that is still way more than the 125 HP it puts down before the VTEC change over. If I can land it at 5200 I put down almost 155 HP.

I made the mistake though when I first got my car of revving it too high. I was racing a buddy of mine with a EK coupe and cammed B16b. We were going from a 60MPH roll and of course I walked him, I kept in third till 8k, and I didn't run out fourth. When we went back and looked at the video though, you could could see him start to pull me right before I shifted, so I know I was going too long. If I had shifted like 500 RPM sooner I would have pulled him harder instead of him gaining on me at all.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by twistedbydezign &raquo;</TD></TR><TR><TD CLASS="quote">

there are quite a few problems, first off the ecu wont let u, secondly the valvetrain will bitch slap u, and thirdly it doesnt make power that high so its useless to do so</TD></TR></TABLE>

LMAO