H22A8 vs H22A7

[chrismc]

My bro has recently bought a BB8 5th gen VTi (H22A8) & previously had an ATR (H22A7)

Both engines have been identically fettled with K&N Typhoon kits & decatted exhausts- but the Prelude has a noticeably more muted induction (despite Typhoon!)

All the basics such as base timing & valve clearances have been verified.

From my research the engines themselves are pretty identical (cams/11:1 c.r etc etc) with the exception of the A7 ATR engine having a single runner intake manifold compared to the dual runner setup on the A8. This is all I can think of that would affect the intake noise?

As such- & given the A7 ATR is rated at 212HP standard and the A8 Prelude @ ~197HP can the dual runner manifold be replaced by a single runner ATR manifold & mapped to give a decent power gain??? (Stock ATR power)

Would appreciate any input!

Cheers

Chris

[lewd lude lover]

i honestly thought most of those ponies were down to the map and not the parts.

the ATR has a much more aggressive map than the lude due to marketing of a type R etc. the lude is a more relaxed car by design.

My type S has a much more aggressive map and i would guess more like the ATR's one as its also rated at 217 ish and feels much more like a rumbling tiger than my housemates A8 equipped UKDM VTI...

[chrismc]

From my experience the ATR map is more aggressive with an immediate noticeable jump by about 20HP as it hits VTEC- not subtle or ideal at all IMO. (marketing ploy no doubt)

The VTi is much more muted & linear in comparison

I can understand the mapping affecting the power delivery- but would slightly less aggressive timing really make the intake so much quieter on WOT?

[Sailor]

From my experience the ATR map is more aggressive with an immediate noticeable jump by about 20HP as it hits VTEC- not subtle or ideal at all IMO.

I like it like this. Even though it's harder to keep it on cam because the cut-in is at higher revs, the surge is fun can occasionally be quite handy.

[Merlin]

Apart from the intake manifold and the head itself (P13 Vs PDE) there isnt much difference. Same 11:1 CR, 62mm TB, and cams. There is rumour that tuning a stock H22a8 will give around 220 once tuned. BennyBoy's tuned H22a8 with H22a7 intake manifold made 244bhp & 173lbft.

http://www.ludegeneration.co.uk/profile ... -t505.html

[chrismc]

From my experience the ATR map is more aggressive with an immediate noticeable jump by about 20HP as it hits VTEC- not subtle or ideal at all IMO.

I like it like this. Even though it's harder to keep it on cam because the cut-in is at higher revs, the surge is fun can occasionally be quite handy.

True enough- I just got fed up with having to rev my ATR to within a gnats of the rev limiter to keep it in VTEC though...

Not normally an issue for a VTEC owner of course , however if it DID drop out of VTEC when caining it, it really did feel flat

[chrismc]

Apart from the intake manifold and the head itself (P13 Vs PDE) there isnt much difference. Same 11:1 CR, 62mm TB, and cams. There is rumour that tuning a stock H22a8 will give around 220 once tuned. BennyBoy's tuned H22a8 with H22a7 intake manifold made 244bhp & 173lbft.

http://www.ludegeneration.co.uk/profile ... -t505.html

Very interesting- any more info on the differences between the heads?

[Merlin]

H22a8 = P13 head same as JDM H22a, a2 and a5
H22a7 = PDE head
H22a (S-spec) = P5P head

H22a7 and H22a8 share the same bottom end - 55mm mains cranks, PDE rods with floating piston pins and PDE pistons

Buzzonion - Do you have any comment on the claim that the only difference between the P13 & PDE is that the PDE has a port and polish? I have read a few sites that suggest this.

There are actually a number of differences between the P13 and PDE cylinder heads but most of them are not performance related and some of them not really worth going into.

Likewise not all P13 cylinder heads are the same !!

First things first.

PDE does not have what I would call a "port and polish". The bulk of the intake and exhaust ports are the same as any other H22 head, ie left as it was cast. It's only really a little bit of finishing work at the valve throat that sets them apart (when comparing bare head to bare head).

Other differences - PDE and 98 on casted P13s (on a H22a8 block) have spring LMAs (lost motion assemblies) rather than the hydraulic plunger type of all earlier heads. The machined housings for the LMAs in these later heads are just about 1.5mm shallower than the early ones. You can still use the later "spring LMAs" in earlier heads but you need to add a flat washer to the underside of them so they work effectively.

PDE heads are unique casting to the intake side which was specifically designed to work with the ATR intake manifold design. It's designed for the unique IACV and EGR system found on the ATR. This doesn't mean that a "normal" dual stage P13 type inlet manifold can't be used on this head, it can and works very well. The ATR inlet manifold will of course also work on any of the H22 variations but requires modifications to EGR, IACV and fuel system.

Here's a couple of pics showing the differences in casting that I've just talked about

PDE Cylinder head (ATR)


P13 Cylinder head (actually a 98 spec P13 from a H22a8)



Is a PDE head worth swapping onto a H22a, a2,a5,a8 - I'd say yes if it came complete with cams and that's all you wanted to do.
But if you were going to port it and add higher spec cams (along with valve springs and retainers) then you may as well just use your existing P13 head (of whatever year).



God... I'm such a geek

http://preludeuk.forumup.com/viewtopic. ... =preludeuk

Extra blurb here as well:
http://honda-tech.com/showthread.php?t=1995637

[4thgenphil]

cheers merlin strangely enough i was just going to look for that ! + rep for being a mind reader

[chrismc]

+1 many thanks!!

Will have to have a chat with Rich next time I'm passing- only 20mins up the road!