Great, so completed table above Theoretically, taking the assumption of both engines being in good condition, that lays out the basis of comparison. Looking around, and bringing in a thread we've seen before, a 9A/ABF comparison, this is surely the basis of the output differences we are seeing: To click back to the original thread, hit the ">" just after 'Posted by daved'
Soooooooo...... theres loads of techie info but never a conclusion for which block is best for a modified 16v pushing the 200bhp mark, Or did i just miss it amongst all the stuff i didnt understand? Im thinking of doubling my 8v's to 16 in the quest for more power now i have a ibiza FR diesel to fulfill my torque needs. It would be running on twin 45's as i have them on the 8v with raised comp and some pretty tasty cams im sure, hoping for around the 200 hp mark. Is one of the blocks a better starting platform or are they pretty much on a level parr for a track day spec engine so to speak? Cheers boffins
Well mods would be some thing like lightened bottom end with 11.5 ish compression, high lift cams and some head work with twin 45's. Basically I would be after a spec to get me around the 200 to 215 bhp mark. Would one of them be a better starting platform?
Everybody talks about the obsession of getting 200bhp from a 16v but what about the torque, you also want to be getting 180 lb/ft from a well built engine.
Is there or another thread on 16v torque/how to get good gains. Should one be started! Apart from using longer duration cams/head work/cr increaces. What else is there? (What i have in my head...may not be correct)
It would be going in a mk1 golf track car, your right brookster I didn't really think too much about the torque aspect of things. At the end of the day all I really want to determine from this thread is which engine is the best platform to use for a modified 16v. I think I'm just going to go the abf route.
There could be other differences... I've flow tested both standard 9A & ABF heads. On the two heads tested, the 9A made 104cfm on the inlet, the ABF made 110. Now that could be the difference between two different castings, or a difference in the two types. That airflow diffence is a "potential" 5hp, but, that could be closed up in the cam & rod angle differences. I'll do some measurements of the std ports/throats at some point, but, when both are ported to the same ballpark spec, the flow in modded form is the same, 136 & 137cfm in the case of the two mentioned (flowbench developed in this case rather than fast roadies)... so it does'nt matter what base head is used between those two. It "may" be a different ball game with a KR casting though... I have one here to test, time permitting.
There is more to such a comparison than just airflow even though very important. It becomes complex when all the default improvements start to interact with ambients, parastic loss and mapping to control the lot. Plus when actually mapping the complete unit in a car, the 9A takes more time to come close to matching the character of the ABF unit.
Just to throw this in: http://www.clubgti.com/forum/showpost.php?p=1353953&postcount=17 + http://www.clubgti.com/forum/showthread.php?t=146656
I think the figures in that link have been calculated based on published factory compression ratios, rather than actually CC checked. Head volumes on all the different 16v heads are to all intensive purposes the same. IE. 45cc
I would have thought there would be little difference in the two heads as well, but on the two heads I tested, there was indeed the difference quoted. I'll try and overlay the two tests later and scan it in.
Nice one. If another later head is flow tested and same trend is found then there is a possiblity the ports on the later heads are also improved from earlier examples.
