Ok so was doing some searching and found the following

My plans were exactly the same lol

So here is the basic Idea

*B20B - 95-98 spec
Keeping to a non vtec build, dont ask why please
*RS Machine Pistons ITR 84mm
*33mm VTEC Intake Valves (upgraded from the 31mm ones)

Noe this guy said that he hoping for much more improvement than what the dyno said think it was like a 5hp gain lol

So my common sense is telling me, that this would be obvious as there is more intake volume coming in but it still need to go out the same 28mm exhaust valves right ?

So what I am thinking of doing is since the intake valves have been increased from 31 to 33mm, the same should happen to the exhaust right so it must go from 28mm to 30mm with ofcoarse using custom pistons or widening the valve reliefs

They said that the vtec head flows much more efficient surly this should aid the b20b head in incread flow

Hope to get some good opinions

Thanks HT Community

 

What is the rest of the build?
My guess is that bigger cams, intake, header, exhaust, etc. would help take advantage of the bigger valves.

 

b20 non vtec with p75 head
headwork with titanium harware
3 Angle valve job
Swirled valves
BIG valves as stated above
45mm 4age Toyota Black top ITB's
Aggressive custom cam
eagle rods
balanced crank
8lb fly wheel
rs machine itr pistons with inlarged exhaust port
racing bearings
baffled sump
adjustable cam gears

with neptune software

 

If I was gonna do the work for a 33/28 non-vtec head, at that point, I would ask the customer, why not just get a VTEC head, put big valve on it, and make 30-40 more hp?

 

I don't believe in the concept "to be different". Many times being different just lends to less power. Now, if less power is the sacrifice someone is willing to make to be different.....then by all means go for it.

 

So everyone should just do the "Cookie Cutter" build??? Your comment sounds very close minded.. That is not the kind of thinking for progression.

 

Its purely science and math. I didn't choose that some heads are more capable than others, their original designers did.

 

the P8R head has vtec sized valves from the factory. it retains the 28mm ls exhaust valves but with a nice port job they flow really similar to a pr3 head. I totally understand non vtec b series builds. you really have to own one to understand I guess. its really not about the power you make.

 

if this is true why is any one in the all motor forum? the easy way to go is ls or gsr turbo on e85. super easy recipe that will make more whp then just about every single build in here for a fraction of the cost.

we all know if your after big power why go all motor?

 

I have to agree with bambam.

If its not really about the power, why build a high performance engine at all?

And saying that we don't agree with doing things "just to be different" doesn't mean we think all builds should be cookie-cuttered. (Though in real racing, you'll find most engines in a series are VERY VERY similar & this is without teams even being able to see what other teams are running. They simply run the numbers for what they are allowed to run & most wind up with very similar designs.)

Handicapping yourself with a non-vtec head "just to be different", is, I'm sorry to say, less than intelligent.if its a budget thing, then I totally understand it, but this guy is talked about adding 2mm bigger INT valves to his head (which would be useless without scaling the port to compliment it). Were talkin at least. $1200-1400 job to do it right. VTEC heads are abpout $400-500.

 

P8R heads can be had for any were from the $50 to $250 range.

 

Valve size alone does not a vtec head make.

Port sizing
Smaller guide diameter
More stable valve train design
VTEC

 

I know Im just saying why spend alot of money converting a ls head to run that size valve when you could just buy a p8r.


you do have to admit though that a big point of being all motor is to be different. its the same concept of doing a non vtec motor as well.

 

I agree

but with the head I dont plan on increasing the size of the ports, I will do all the work on the area by the valves

here is a nice read on head work

http://www.prelude power.com/forums/showthread.php?t=240061 - remove the **** to see the link

I will try my best to locate the P8R Head but seems like all the motors imported to SA are the low comp versions

One thing about the P8R Head is it has the bigger valves I do understand this so therefore it should have superior flow design compared to the P75 right ?

 

That is not why I spend my time in here nor why I build/run all motor setups. It is because the people who are in here are generally more sophisticated. I also like the sound/reliability/drivability of an all motor setup. Anyone can stick a snail under the hood and turn up the boost. Easy.

 

Good luck finding an importer that even knows what a p8r head. Your best bet is here or ebay. Also keep in mind p8r heads are 84mm combustion chambers. It will effectively lower your CR .4 points. I wouldn't recommend running it on an 81mm bore either, although there is one person on here doing it, we'll see how long it holds up.

 

Haha its all good buddy, to be honest I am quite keen on using the P75 head with the bigger intake and exhaust valves , gonna take it to my machine shop to see what they suggest

I see that the combustion chamber of these b20 heads is actually 81mm while the gasket is 84mm

makes sense from your thread, what you were saying math the gasket to the block not to the head !!!

I also found proof that the P75 has smaller ports than the PR4, PR3 and P8R which should mean tighter flow in the head

This is mostly for experimental purposes and the best part of it here in SA you can pick these heads for dirt cheap as everyone is on the b20v craze

 

since we on the topic how much do flat faced valves increase your comp ratio by ?

 

With the exception of the p8r equipped b20's, b20b/z motors are 84mm b18b's. Hence why it has the same head. B20b's also had a different intake manifold.

 

same can be said for the ones who say simply slap a b16 head on it.. it will make more power. that is obvious and maybe some people find it more sophisticated to build a motor that takes more effort to make good numbers like a non vtec motor. (same idea behind making a 200whp b16 motor) as for reliability and drive ability a mild turbo motor with a proper sized small turbo will be leaps and bounds over a na setup for drive ability as well as low end tq.

 

You win. Ill stick to my superior vtec heads.

 

My point is using a superior design over an inferior one. For comparison's sake...think t3 turbo vs. Gt35. If you want to see what you can get out of that T3, by all means have fun. Ill stick to the gt35 that can support my demands/goals.

 

Ok we all know that the vtec head design is far superior to any bseries non tec

but honestly you have to admit, that you would be interested in the numbers this car could produce !!!

Anyways

Found some info on the ls head seems like it has larger ports than the b20 but the coolant passages are inferior to b20

got these off another site I think this guy is here too got some awesome vdub volksy




here is the combustion area of the p75 and PR4

 

found this by the way

http://www.youtube.com/watch?v=vEutvZXAQQc