20v head on 16v block

[quicklvn]

Hey guys,

Yes done a search and found relative material but not quite what I was looking for.

After watching a video of a race at the tskuba circut (all AE86's), I noticed that the majority of the cars were running 16v blocks with 20v heads.

I have a 16v smallport redtop that i'm putting into my AE85. I'm going to get ITB's and a cam grind already as I've got a link to run it all and I was thinking, how hard would it be to get a 20v head and do the cams on that instead? I'm already using silvertop rods and pistons.

Also any opinions if I would be better to get pre made cams (i.e. TODA) or is a grind of the stock cams just as effective/safe?

Cheers

[thaphatty]

Hmm, see if this thread answers any of your questions

viewtopic.php?t=51428&highlight=

[slighty_sykotic]

Umm, if your running silvertop pistons and rods... And you put on a 20v head....

You have a silvertop already.

Blocks and cranks are the same.

Run a 20v ecu and you won't need a aftermarket ecu (as you would if you ran ITB on a 16v head) as long as you don't go crazy with the cams.

--Sykotic

[RedMist]

Hey guys,

Yes done a search and found relative material but not quite what I was looking for.

After watching a video of a race at the tskuba circut (all AE86's), I noticed that the majority of the cars were running 16v blocks with 20v heads.

I have a 16v smallport redtop that i'm putting into my AE85. I'm going to get ITB's and a cam grind already as I've got a link to run it all and I was thinking, how hard would it be to get a 20v head and do the cams on that instead? I'm already using silvertop rods and pistons.

Also any opinions if I would be better to get pre made cams (i.e. TODA) or is a grind of the stock cams just as effective/safe?

Cheers

How can you tell they are running a 16 valve block? Are they running 3 rib blocks?

[slighty_sykotic]

Maybe they're running bluetop cranks and rods for lightness? So yeah, 3 rib blocks.

[quicklvn]

It just said on the spec sheet: Block: 16valve AE92 etc
Head: 20valve AE101 etc

Like that, then it went on to list the cam specs etc.

What I was really wondering is if I will get more power with a 20valve head with a cam grind or a 16 valve head with a cam grind. (logic would say the 20 valve).

Also if I do use a 20valve head i'm going to have problems with the distributor and the firewall aren't I?

[Bling]

standard to standard, you're right 20v head is better, its only if you start modifing the head itself this "may" change.

get a blacktop head and be done with it

[Stealer Of Souls]

I'm probably gonna get slammed for this...
But from what I can see the majority of power improvements comes from the CR and cams.

I've got a smallport bottom end with bigport head and I've got 82.4kW @ wheels (TP dyno) which is getting pretty close to the 100kW rating of a smallport.

[SpeedRacer]

this maybe crap but im pretty sure I heard it on here and may be the reason bazda is running a blacktop head but not sure.

out of all the 4age heads in standard form the blacktop head flows the best followed by the silvertop thethe 16v heads (not sure which but pretty sure smallport is better than the others).

But when they get modified the 16vs are better.

like I said this may be crap but im sure I heard it on here. someone correct me if it is

[vvega]

this maybe crap but im pretty sure I heard it on here and may be the reason bazda is running a blacktop head but not sure.

out of all the 4age heads in standard form the blacktop head flows the best followed by the silvertop thethe 16v heads (not sure which but pretty sure smallport is better than the others).

But when they get modified the 16vs are better.

like I said this may be crap but im sure I heard it on here. someone correct me if it is

prove to me that a modded 16v is better
if you cant then STFU

[atmosports]

Been there & had this argument plenty of times & to be honest I can't really be stuffed with it anymore. But from my own limited flow testing/research & the numerous times I have discusssed this with Lynn Rogers & a few other people one of whom actually does a lot of cam work for some name brand Japanese companies, yes in stock form the 20V heads have more flow, but in modified form(never discussed how radically modified) & I'm saying here going for maximum power/flow/velocity a 16V head according to a flowbench & what I've seen on the dyno will outperform a modified 20V head but then the 16V heads have been around for longer & more people have played with them etc. That's just my 2c worth & to be honest it's like comparing cock sizes as no one races flow benches or dynos but it'd make my life a damn sight easier if we did.

[vvega]

lol

basically
n/a
16v wins the crown....by a few hp
turbo
20v wins.......buy a few hundred

[SpeedRacer]

prove to me that a modded 16v is better
if you cant then STFU

sorry i should have worded it more like a question asking if this was correct more than a statement saying it was. I thought i had heard something along the line of what atmosports was saying but wasnt sure it was correct or not.

sorry

ill stop talking now

[vvega]

it was blunt
not ment to to be nasty

v

[quicklvn]

Ok I have now been offered a bigport head that has a kelford cam grind and been ported etc of a rally car.

a) Is this compatable with the smallport block without modifications? (fairly sure it obviously will).

b) Can I still run ITB's as easily as I could with a smallport head, and will they be as effective?

Sorry about all the n00b questions as previously stated im still learning as I go.

Thanks for your patience guys.

[no_8wire]

Some one PORTED a bigport!

[thaphatty]

A) yep, but you'll need to block of the oil drain on the block, (unsure about drilling hole into side of head )

B) Will be just as "easy" to run ITB, as for effectiveness, id say that would depend on your cam and your porting

and no_8wire - It wouldnt suprise me if someone had started with a bigport, filled in the ports with whatever the head blog crap they use is, then ended up with ports smaller than a small port. My old bosses AE86 rally car is like this, ports ended up kinda similar shape to small port, but higher up on the head, even though it started life as a bluetop.

[quicklvn]

Thanks for that,

How would I go about blocking the oil drain? Could I not just use an oil catch can etc (or am I thinking of the wrong thing here).

For specs check out the auction:

http://www.trademe.co.nz/Browse/Listing ... d=87490567

Good buy? I think it seems quite cheap for the work done.

[RedMist]

A)
and no_8wire - It wouldnt suprise me if someone had started with a bigport, filled in the ports with whatever the head blog crap they use is, then ended up with ports smaller than a small port. My old bosses AE86 rally car is like this, ports ended up kinda similar shape to small port, but higher up on the head, even though it started life as a bluetop.

Shit... that sounds like my old 4age race engine (now sold to the Wellington region). I didnt realize that the technique was that common.

[thaphatty]

Thanks for that,

How would I go about blocking the oil drain? Could I not just use an oil catch can etc (or am I thinking of the wrong thing here).

For specs check out the auction:

http://www.trademe.co.nz/Browse/Listing ... d=87490567

Good buy? I think it seems quite cheap for the work done.

Seems cheap enough to me provided its straight and true and in good nick. Motors only as good as its builder though.

Some people use the oil drain setup for having a return for oil surges between the pcv/intake manifold for track use. On a turbo setup it would be a good place to vent the sump from, in either case id be inclined not to block it off entirely - although there may still be sufficent ventilation from the oil return holes on the side of head.