want to build an engine :)

craig_jdm · Post by **craig_jdm** » Fri Mar 15, 2013 12:17 pm

i would look into getting the full a7 head as it gives you the option of bolting an a7 inlet mani straight on and TB rather than goin for a skunk 2 mani

A1ex · Post by **A1ex** » Fri Mar 15, 2013 12:20 pm

craig_jdm wrote:i would look into getting the full a7 head as it gives you the option of bolting an a7 inlet mani straight on and TB rather than goin for a skunk 2 mani

That's what I did and I got the ATR throttle body, injectors, fuel rail & inley mani in one hit on ebay. You'll need a custom fuel line to do it that way the the ATR injectors give a better spray with the ATR mani.

Also, the ATR head has had a mild Port & Polish and different valve seat angles IIRC

leefentonsheard · Post by **leefentonsheard** » Fri Mar 15, 2013 12:34 pm

the heads are the same and all the valves ive got an a7 head and an a8 infront of me and there is no difference at all haha im led to belive its only cams and crank that are different in the engines then clearly inlet and throttle body am I right ?

A1ex · Post by **A1ex** » Fri Mar 15, 2013 12:41 pm

a7 & a8 engines are the same. But they're higher spec than the a5 & a2 engines

craig_jdm · Post by **craig_jdm** » Fri Mar 15, 2013 12:53 pm

the a7 inlet is slightly different if i remember the a7 inlet mani and fuel injectors do not bolt straight on the a5/2 head they require machining

Post by **Merlin** » Fri Mar 15, 2013 12:56 pm

leefentonsheard wrote:the heads are the same and all the valves ive got an a7 head and an a8 infront of me and there is no difference at all haha im led to belive its only cams and crank that are different in the engines then clearly inlet and throttle body am I right ?

There are slight differnces. The a8 uses the P13 head while the a7 uses the PDE head. Both use the same cams and 55mm crank, both have a 62mm throttle body, but use different intake manifolds. The differences between the heads is the reason why the ATR intake manifold requires a little machining to bolt up to the Lude P13 head.

PDE Head intake side

H22a8 P13 Head intake side

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

Really though all of this means squat is you are planning on a major build as you would be replacing pistons and head contents. So starting with an a2, a5, a8, a7 doesnt really matter, unless you care about having a 55mm crank

leefentonsheard · Post by **leefentonsheard** » Fri Mar 15, 2013 1:14 pm

oh I see haha I measured the cams from an a7and an a8 and they are ddifferent the a7s are bigger

Post by **Merlin** » Fri Mar 15, 2013 1:19 pm

Could that be due to wear on the a8 cams? Either that or you don't have a8 cams.

The whole a7 / a8 / Type-S cams being the same has been common knowledge for a quite a while and has never been corrected by the H22 god (Buzzonion Vtec / Performance Autoworks), who usually sorts the mis-information out.

leefentonsheard · Post by **leefentonsheard** » Fri Mar 15, 2013 1:30 pm

yes it was close and the a8 had done over 230 thousand lol :/