Oversize Valves - The easy way out

[Adam.Findlay]

also keeping a very close eye on this thread
http://ozvr4.com/forums/showthread.p...ghlight=plenum

if they can make a good plenum with say velocity stacks inside on each of the 6 runners that definatly would help

[Spetz]

To be honest looking at my 6A12 plenum it does seem to be far from ideal and I feel that there are definite gains to be made with a well calculated plenum.
The 6A12 plenum for starters has the dual length runners and when it switches to short there is a butterfly on each runner which opens, but that in itself seems to be quite a restriction. The design of the plenum itself does not seem to be ideal, and there are no ram tubes. I cannot comment on runner size but I think this is less of an issue as generally the runners should be about 10% larger than the valves, but they are definitely a bit long in my opinion which is again not ideal for a high revving motor which is mostly about top end power

[zentac]

didnt bother looking at billett ones as regrinding stock cams will give more then enough lift and duration



have priced custom valves from the local cylinder head specalist and at $40 per valve and 24 valves it adds up pretty fast, and you still have to add head maching ontop of that so easier to buy 1.5 sets of evo valves @ ~$270 USD a set and get 1.5 sets of evo valve guides ~$80USD a set



I understand all this and yes I am young but (without sounding cocky here) consider myself pretty clued up on engines and the like, being a mechanical engineer student I have developing materials know how.
as I said they are just "goals". I will be more then happy to settle for 500hp if the stock crank cannot handle more, with when I finish my degree and get a propper paying job i can afford extravigant parts such as forged cranks and the likes. but for now i can live with scale back the build for cost purposes, in saying that I am in no rush I have an open ended timeframe to complete my project.

Richard or ZENTAC does have in my opinion (hope I dont get flamed for this) a bit of a jaded opinion on the 6A13tt, yes he had a forged shortblock and bigger cams with a huge turbo, but he also used standard valves with standard plenum so he didnt really fully explore the limits although he did highlight some weaknesses while he was at it. must have just hit the 600 number and given up.

but the main point of most of these threads is for the greater good of the club, finding different more cost effective ways of modifing the 6A13TT for anyone who is willing to take on such extensive modification. hopefully be able to keep up to some of the 1jz/rb26(25) guys

I loved the 6A13, otherwise I wouldnt have stuck with it as long as i did. The problem is not with the crank itself its with the cradle, and the number of retaining bolts it allows the crank to flex too much, the same will happen to a forged crank just take higher stresses/rpm to get there. Same problem as the GTO has

Having looked at the heads we decided there wasnt enough room to get 1mm oversized valves in so it will be interesting to see if you manage it. You may end up machining the pockets in the pistons to take a bigger valve.

Ben did a new plenum for his 500+ bhp VR4 FTO, I personally dont think getting air into the engine would have been a problem until you hit 7-800bhp

My 1000bhp plenum on the EVO engine holds about the same amount of air as my old VR4 plenum, when you include runner lengths etc...


We recorder 560bhp and 485lb/ft torque at the hubs on a Dynapack Chassis Dyno Peaking at 2bar (30 psi) holding at 1.7bar. That is estimated at 630bhp and 545lb/ft (figures yet to be beaten )

[Adam.Findlay]

Scott and i were running off ideas and he suggested that the block could be drilled sideways to effectivly make the block 6 bolt mains. like a LSx or 1UZ engine, that could help with mains rigidity,

http://www.engineeredvictories.com/images/LSx/026. -6 bolt mains
if the crank is not the weakness then possibly a billet mains cradle could be a significant advantage and possibly cheaper then a billet crank

[zentac]

Scott and i were running off ideas and he suggested that the block could be drilled sideways to effectivly make the block 6 bolt mains. like a LSx or 1UZ engine, that could help with mains rigidity,

http://www.engineeredvictories.com/images/LSx/026. -6 bolt mains
if the crank is not the weakness then possibly a billet mains cradle could be a significant advantage and possibly cheaper then a billet crank

now theres an idea i didnt think of, but how would that help as the 2 middle cylinders have no where to strengthen them?

[Adam.Findlay]

IMG057.jpgIMG061.jpgIMG058.jpg

[Adam.Findlay]

possibly not due to the gap between block and mains cradle. hmmm

[Adam.Findlay]

After A very large deviation away from the threads intended topic. I took the evo valves in to peter kennard from kennaly cams and he said the 5mm longer evo valves will become an issue so he could either machine the evo stems to be shorter and turn a new collet grove onto it for around $450 for 24 valves then there is the cost of buying 24 evo valves @1.5x280 USD and the cost of fitting them into the heads
or he can supply 3mm oversize inlet and exhaust valves from some kind of subaru for $495 NZD plus the cost of fitting them to the head

[Kenneth]

Does he do porting also by any chance? There would be SFA point in spending the cash for all that and not doing some work on the ports at the same time.

[Adam.Findlay]

he should do. As today is his last day at work before christmas i wont be going in and bothering him but if anyone is intrested and wants me to ask him some more questions about the matter i will be more them happy to. and if he doesnt do it he can just supply the valves and CHS up the road can do porting.