I'm running a stock obd0 pr4 ecu. Motor is a b20b nonvtec. Here are the questions.......

1) Do these ecu's have a cold rev limit and a warm rev limit that is different?

2) If so what are the REAL limits set by the ecu (I want exact numbers...not...well my tach says 7k)?

3) With stock rod bolts, how high have people rev'd their motors and not had any problems (I know it is a stupid question but I need to know)?

4) With ARP rod bolts...what is a safe rev limit on stock rods?

I will explain the questions as I get answers...no bashing please

 

I thought B20s have problems with floating and dropping valves... at high revs...

should have a rev limit of 7200rpms... stock PR4 is a B18 ecu...

 

From my research it says that a pr4 ecu rev limit is set at 6912 or something of that nature.

I ask these questions for many reasons...

First, with my b16 ys1 tranny and 195/60/14 tires I top out at 93mph in 4th and 114mph in 5th at what I think is about 6900rpm. I am trapping at 92.4mph topped in 4th with minimal time to shift to 5th...if I do it lowers my ET. I am ordering a chipped ecu from xenocron with a raised rev limit. I am going to have the limits set at 7100rpm and another chip that is set at 7300rpm. I am only going to use these while at the track and while going through the trap in 4th.

I've free rev'd a b18a1 motor to 8k and 9k rpm quite a few times...sometimes just dicking around other times missing shifts. I also have sprayed that motor with a few bottles with a 85 shot...it runs my friends crx daily.

I've rev'd my b20b powershifting (free rev basically) to 8k quite a few times with NO issues.

My philosophy is that free reving these motors (although not good for them in the least bit) does not lead them to snapping a rod bolt/rod. You would have more of a chance of floating a valve while free reving that high.

Well I am wondering if this b20b motor will handle the extra 300rpm above stock revlimit while under load just in 4th gear (and i know the higher the gear the worse the load on the motor). This isn't going to be my daily but obviously I don't want to buy another motor right this second (in about 6 months it will be fine lol).

I believe that since it will never see those rpms on the streets and only a few times at the track (most likely a max of 12 passes within 3-4 months time) that the motor will be fine. What does TR think?

 

90 LS. Redline is at 6,800. The 7,200 rev limit was for the 94 plus LS's

 

u need a ls tranny.. longer gears.. vtec trannys on non vtec motors dont match and the other way around.. unless ur planing on going vtec soon..

 

I'm not going vtec but this tranny shave off like .3 in the quarter so the LS isn't going back on. I think I'm just going to order the ecu and if I blow her up then I blow her up. I'll post back lol

 

lol dont blow it up!! it shed .3 but did you topped out with the ls tranny??

 

I never ran this setup with the LS tranny. My old b18a1 with LS was only pulling like 87 in the quarter but this setup is going 93 and it would be faster if I wasn't topping the tranny out.

I doubt it will blow up only being brought to that rpm a few times and I'm going to "tune" it with the afc.

Do you have proof that the b18b1 revs to 7200rpm? As in have you used a digital tach to measure it with? If your using the stock tach and telling me it revs to 7200 then I'm not going to believe you lol...my tach says 7100-7200 redline with my pr4 ecu and I know its around 6900 but yet my tach idles at 750ish...stock tachs blow.

 

yeah dont believe the stock tach no accurate readings ever!!.. but i would think with an ls tranny and the current set up it would make better numbers and no topping out.. add a 75 shot of nitrous and ur gonna be looking at way better times..

 

lol...it's going to see nitrous as it sits not...and it will be fast as fuck as it sits now

I'm going to spray her with about a 55-60 shot pill and its going to see a hytech replica header along with a new skunk2 proseries manifold and throttle body.