I was thinking today since the b20 block only good for 7200rpm with a vtec head can it be made into something like a d15z1 motor?

have the cams that would give nice gas mileage in lower rpm and have vtec engage at around 3500rpm or 4000 rpm and have a decent vtec lobe for that compression.

im talking about a completely stock b20v someone that just put a gsr head on it and wants to keep stock b20 redline .

what cams would work good for that purpose?

 

well, OEM GSR cams are a good starting point.

Theres no reason to do a vtec conversion and still be limited to 7200. Thats whats called half assing it. If your going to build a B20 vtec, build it right the 1st time. Get the cams needed for the compression your going for. get the rods resized for ARP bolts and you can do the YCP ITR reps for a budget build. Theres no need for forged internals for a decent street engine and cast will be fine.

Theres no need to do the build twice. Plan, save $$, buy your parts and when you have it all done, get it assembled.

 

I meant if I had a good clean block and stock gsr head.
the super budget build lol

 

I'd run with the GSR cam.

Now one thing got me thinking. If you are planning a stock b20-VTEC for simple daily use with a very conservative max rpm, which cylinder head would be better? There are differences on the intake side of the heads. Not to mention the difference in intake manifold design. Would the lower angled pr3 intake port with its narrower intake manifold runners be better than the gsr with its higher angled intake port and dual runner intake?

Cams are one part of the story but how would the heads play into this? I'm going to take a guess that you are most concerned with power under the curve rather than peak numbers.

 

I believe you are actually limited to the B16 or GSR cams. Anything bigger has p2v problems with those little, tiny valve pockets in the OEM B20 pistons. You MIGHT be able to get away with Type R but the clearances would be super tight.

Stock GSR head on a B20 runs great though. Tuned they make good power, good fuel economy and very reliable.

 

The OEM B20 pistons have a lower height then ITR reps.. not by much.
I think its 29.59 for the P3F/PHK pistons. 30.06 for the ITR reps.

 

I've been running ITR cams in my sotck B20v for four years now. It makes peak power at 7500 rpm too. As for mileage, I was getting around 34-36 mpg.

 

The B20 oem pistons have a height of 29.59 and the ITR reps are 30.06, so its not much, but can make a difference.

I still say to plan it out, do it right and youll be rewarded with with a decent street engine that you can daily w/o problems.

Heres 2 threads you should study
https://honda-tech.com/forums/all-motor-naturally-aspirated-44/how-build-%22reliable%22-lsvtec-b20vtec-1676914/
honda-tech.com/showthread.php?t=3102979


CR w/ P3F - 9.36
CR w/ PHK - 10.28

This is also with a head shave @ .010

 

^^worth repeating.

I hand-enlarged the valve reliefs on a B20Vtec I did for my nephew. He didn't change out the pistons; so to be safe, I hand-ground the reliefs bigger and deeper.

 

Just like everyone says. ITR cam max unless you swap pistons out or enlarge the valve reliefs.

 

how hard does the power/tq fall off after 7500. its got me curious.

<--currently running itr cams in ls/vtec

 

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