4A-GE 20v oversize valves

[johnny]

The head will be heavily modded and the exhaust valves need to be bigger.
I'm not going to debate with you guys on this one

If my engineer says, get bigger, i'll get bigger to him...

Hate to shock you, but you'll go backwards in HP in a big way, We've be stuffing around with 20V for years and the best combo is leave the alone!, ever time some one has had the idea is how it end up... Not many people know how to play around with these engines and make this work.

[Toycrash]

Hi Johnny!

What kind of setup you have done?

Cam lift/duration, what pistons and most of all how did you make your exhaust headers work

My engineer stated, that he never in his long history of building race engines, he havent found a such engine that has as much trouble with headers.

If you dont like to tell it to all of us, gimme a pm.

[Mr Revhead]

what kind of trouble with headers?

[RONA]

toycrash welcome to the politics of toymods
=)
u have pm

Rofl and toycrash try and get any info you can off this man, 133.4rwkw out of a NA 20V says he knows what hes talking about.

[myne]

Wow that is impressive. Almost makes me ashamed to have a boosted engine - specially since it's not as powerful as that :/

[Toycrash]

what kind of trouble with headers?

Tuning them is a troublesome
Size, length, collector length, collector shape...

3mm change in collector length gave 10Nm on one engine

[Mr Revhead]

which is why most aftermarket ones tend to be worse than the stock ones....

that kind of experementaion can get costly :S

[johnny]

Hi Johnny!

What kind of setup you have done?

Cam lift/duration, what pistons and most of all how did you make your exhaust headers work

My engineer stated, that he never in his long history of building race engines, he havent found a such engine that has as much trouble with headers.

If you dont like to tell it to all of us, gimme a pm.

Ok I'm trying again since you guys didn't get my last reply. Yes your engineer is right, the exhaust headers are the key to these. The design we use is based on an old 50's era hot rod design that came about in the USA. This is not my area, but my tuner who does the figures etc. A standard 20V which made consist 88HP@wheels made 120HP@wheels with cleaned up ports and his headers, the same one made 95HP@wheels with off the shelf A/M ones. Cam Lifts/duration, well depends on what your aiming for? My personal ones are for rally, so I want something with go torque and power. I have two ATM, ones a mix, Blacktop bottom, silvertop top+ B/T Cams and throttles, all standard parts were used and I'm still waiting to find out the results. However the results of how it was before a bearing a let go just before Xmas as above and , hence why I have a "bit-sa" from what I had lying around. The other which has had everything change,(Piston, rods,cams etc) is based on another 20V in a starlet circuit car,consistently pulls 120+kw depending on fuels, still has VVT connected... specs on this I would love to tell you, but I'll be killed shortly afterwards, so toycrash email me ([email protected]) and I'll give the email to my tuner who'll fill you in with the details on the headers and I tell you what we have done in the way of my engine, which really is nothing new, just a lot of cash....and

Rofl and toycrash try and get any info you can off this man, 133.4rwkw out of a NA 20V says he knows what hes talking about.

Bet it Revs into the twilight zone, So Don't expect to be paying anything under $10K to get these results... I would of like to have been at the last few dyno days, but they have seemed to fall on the wrong dates for me and Doing a master in finance didn't leave me much time to get out or fix my cars , this year well? I'll see how it goes.

[Celica RA45]

ferrea do 2mm bigger valves for inlet and exhaust and 1 of my friends has been using these valves in black top race motors for the last couple of years even porting the heads out to get 240 hp at 400 th lift in flow bench tests ,seems to know his toyota motors

[Dimitri]

if you have faith in your engine builder then i say go for it.

i wouldnt put too much emphasis on the fact trd dont supply o/s valves for the 20v.

aussie engine builders have been selling japs motors for years..

maybe try to speak to yager, there are alot of race clubmans running his 20v's.

this is greatly over simplified, but if a 16v 4ag can benefit from bigger valves on in' and ex' (which it definately can), then i dont see why the ex' side of a 20v wouldnt. the ports on the ex' side of a 20v are very similar to the 16v.

[johnny]

maybe try to speak to yager

got it in one

[terryo]

I've built a few stock & race spec 20 valve engines. I 've not used or heard of o/s valves but would make them without much trouble. getting a good blank will be the hassle, as they are more like motorbike valves, for which you rarely can get blanks. Try Ferrea in USA for these blanks, or their custom service (RA45 has also suggested this firm) . I agree the exhaust design plays a big role. We get to 210-220 flywheel HP quite easily, then the details like exhaust, intake trumpets, port shape etc take over. I have a couple of well developed camshafts for these engines. The wrong cams make the engines very "peaky" to the point they are hard to race as the power band gets so small. I have just built an experimental 7A 20 valve "blacktop" with radical crank, rod & head changes (but stock valves). should have it on a dyno in a month or so.

[johnny]

. I have just built an experimental 7A 20 valve "blacktop" with radical crank, rod & head changes (but stock valves). should have it on a dyno in a month or so.

Interesting...I would like to compare your figures when its up and running as I know of another which will be finished at about the same time, similar mods too. This is the second one, the first never made it off the dyno, but used a S/T head. My question is using the 7A block are you going for cubes or rod to stroke ratio? The S/T was trying to achieve Rod/stroke, but dropped a valve during tuning, this B/T is all about cubes (approx 1.9L). If yours is along a similar thought, may be we should get in touch. I've supplied all the parts as a sponsorship arrangement for this engine and I know it is well under way of being built... it would be a good yardstick for ever has there's running first.

[terryo]

I was talking to a specialist importer today and they just received stock of 1-piece , 0.5mm oversize stainless valves for 20 valve. email me at work if interested. [email protected].

johnny, i must be a old and slow, but what is a S/T head and what does B/T mean????. I have used rods 1mm shorter than the 7A ones so I can work on the piston crown a bit. I have left the stock 7A stroke but radically changed the crank.

[Celica RA45]

gee terry b/t means black top s/t is silver top hope this helps ps did you get the new racks as of yet with the extra 3 teeth cut in them