Bigger Valves Vs Reground camshafts - VVTi 4 valve per cyl heads

[mattysshop]

Just wanting some advice from people with more knowledge than me..

mild reground cams vs slight valve oversize - not really engine specific any modernish (dual VVTi/high compression)

makes things hard when you choose to modify shit nobody has ever bothered with, only because there is much better engines to begin with... but hey i like being different

Pro's and Con's of both - the head is getting reco'd anyway.

and i know it's not going to make 100hp extra 'just' from this.. or any combination of both.. just a little bit more 'fun' than normal to complement piggyback ecu, and ITB's.

[mattysshop]

Most of the stuff floating around on the net and anicdotal advice is related to pushrod v8's, and 20+ year old twin cam 4 bangers - ie Mazda BP engines, 4AGE's etc etc..

[andrew_mx83]

While i have no experience with vvti stuff, i would go cams over valves any day. valves will give you a small % increase at best, whereas a new cam profile can completely transform an engine.
Bigger valves also require the head be ported to suit ($$$), if you stick a bigger valve in the same size hole i dont see how you will gain much if any flow at all.

[lexsmaz]

What power & how much more than a stock motor are you aiming for ?? & what are you going to use the motor for ?? As in my eyes unless you want to Rev it harder to get the gains from bigger cams why bother, but that's my thoughts & if its a track car etc then its certainly worth doing something & as Andrew said bigger valves will probably not do a lot without some port work & as with bigger cams will bring the power / torque band up in the rev range & the bottom end will suffer to some degree, being a VVTI motor the cams will probably not effect the low done power as much as a Non VVTI motor ..

[mattysshop]

*awaits everyone to say don't even consider doing anything but throwing in the bin* put a 3sge in.

1G-FE, so 160hp, 11ish:1 static CR, vvti, Looking to fab a manifold and use rb26 or 6 4a itbs (ditching the flyby wire) and some form of ecu to add an idea speed controller & tune the map around the itbs.

Keeping 7-7500rpm max with cams, or 7 with stock cams - would just need to see where power drops off, would hope to see 185hp? Surly not a big ask.. I have been doing some comparisons with NA rb20de.. And 200 seems extremely easy, but cams are available everywhere.

Car 6spd is200, 4.55 diff.

[oldeskewltoy]

bigger valves also mean new pistons to clear the O/S valves.... **IF** needed.

O/S valves are mostly a waste without porting to suit. Since you are running a piggyback anyway, I'd say cams.... BUT... at some point... O/S valves would likely gain more... but that point likely still hasn't been reached.


Since you are doing a lot of fab work anyway.... why not run a GG head, then you can do most of the wonderful 4AG stuff to the GG head... I'd say 185hp shouldn't be too tough

[MorGo]

Proper cams definetly. Even as a head porter I say the head is last thing limiting power.
Some 270-275 degrees and over 9 mm lift you are in business..
Civilised enough for normal trafficking but floored above 3000 rpm and fun begins!

[mattysshop]

fair call.

OST - would have thought the VVTi F head (although an F head) would greatly surpass the 15year older G head, efficeintcy and VVTI.. the best older NA GE made about the same power anyway, but the torque curve is greatly different, the FE has more static CR, and VVTI. i would say some light porting wouldn't be out of the question - like everyone, i have a mate that could help me out with that.

MorGo - the only thing i can get is complete new billets made, weld on to the stock ones/reduce the base circle.. there is absolutly nothing available for them off the shelf, which doesn't really worry me, there are still a few camshaft companies floating around.. i have no idea on the stock specs though..

i am trying to get a hold of a spare complete head to build/use as dummy for the ITB manifold etc..

[oldeskewltoy]

fair call.

OST - would have thought the VVTi F head (although an F head) would greatly surpass the 15year older G head, efficeintcy and VVTI.. the best older NA GE made about the same power anyway, but the torque curve is greatly different, the FE has more static CR, and VVTI. i would say some light porting wouldn't be out of the question - like everyone, i have a mate that could help me out with that.
.

1st... I've NEVER had a GG head in my hands.... my ASSUMPTION is based entirely off of the 4AG head, what the engine was capable as delivered... and the improvements that made it capable of producing 120% more power then it was delivered. Similar head design in the GG, so similar results might be achievable. @ 160hp, a 1GG is "mild", so a 25% boost should get you there... getting 25% from 4AGE is often easy........

[mattysshop]

i see where your coming from now, it would be interesting to see both the late model G-FE vs the G-GE head on a flow bench.

i still have this little thing on my right shoulder saying - just put a 3SGE in it........

if i work it out on paper, it would probly cost the same/similar, and make more power, and be more reliable/drivable...

[jonathan yee]

Lol, i once looked at the specs between the 3sge and 1g. I dont understand why toyota persisted with the 1g. Surely its was more expensive to produce? Once they had the beams they should've ceased production of the 1g imho, obv i must be missing something.

Dude i know just fitted a beams into a spacia with cams and itbs etc. Cant remember if i got a dyno pic somewhere. Is fun tho.