Unequal camshaft duration 4AGE

[toddw]

I am at present looking to purchase new camshafts for my n/a 4AGE that I am building at the moment. I have done a lot of research wrt lift and duration and have seen a lot of guys are using a higher more aggresive duration(usually one step up) on the inlet as opposed to the exhaust cam. I was planing to run TODA 288/8.5 on both inlet and exhaust but am considering going to 304/8.5 on the inlet and 288/8.5 on the ehaust. I am led to believe that even with a higher duration the torque curve is moved higher up the RPM range by using different durations it will broaden in that RPM range. Has anyone had any experience with running higher unequal durations.

To help with my question I will give a quick rundown of the specs. of the engine: 81.5mm bore, Arias 10.5:1 pistons. The head has beeen decked to achieve 11.2:1 compression. I have Pauter forged billet conecting rods, bigport head with very minor porting and stock valves. The engine has s/t quads and will run a Haltechx6 which I am saving up for at the moment. I am trying to achieve the 180-200 hp mark which I thing is achieviable. The application is mostly hillclimbs and sprints although it is still registered.

Hope someone can help.

[toddw]

Does anyone have any info. on this???

[Screamn_Sleeka]

FYI: 4A-GE 20v's run 180hp almost out of the box.

[oldcorollas]

FYI: 4A-GE 20v's run 180hp almost out of the box.

closer to 140-145 from ones that have been engine dynoed no?

\/\/\/ ever heard of one being engine dynoed to 160hp?

[Screamn_Sleeka]

120kw out of the factory = 160hp, there a few people on this site with few mods getting 180.
The recent "beyond 200hp" thread strings to mind.

[smitco]

120kw out of the factory = 160hp, there a few people on this site with few mods getting 180.
The recent "beyond 200hp" thread strings to mind.

I was disapointed with the 20v,llittle torque and power until 4500,all good if ya keep it between 4500 and 8500,even then it is not real good for offroad racing,I think the 16v is a far more grunty and capable engine,Mine was stock with short exhaust,tvis removed and aftermarket computer,exhaust ports ported(leave the inlets)it shat all over the 20v for grunt,REMEMBER 120kw AT 8000,ONLY AT 8000!!!!!

[oldcorollas]

back on topic (a bit)

anyone remember "Robs" pages that had dyno sheet sfor different cams?
was that for 4AG or for GZE?

i might try the way back machine (www.archive.org) and see if they can be dragged up


http://web.archive.org/web/*/http://....com.au/~robs/

[toddw]

I have heard that the torque range will increase with a different duration combo but have no personel evidence off this. It would be good to have the advantage of the high lift/large duration cams without being peaky - by spreading it across the range. It may be worth a try as I am about to purchase my cams.

[Adsport]

hi,im running 264 in 256 out on stock(ish) gze (AW11) , works fukn brilliant! engine retained driveability it had before but revs to the shithouse and doesnt want to stop. idle and low throttle are very nice to drive, torque is very linear. people said that it wouldnt work and it would run like crap and i should really run them the other way around , havent seen any evidece to prove that how i have i setup is scientifically wrong so far bt it DOES behave better than ones setup with the cams offset the other way.

[kingmick]

hi,im running 264 in 256 out on stock(ish) gze (AW11) , works fukn brilliant! engine retained driveability it had before but revs to the shithouse and doesnt want to stop. idle and low throttle are very nice to drive, torque is very linear. people said that it wouldnt work and it would run like crap and i should really run them the other way around , havent seen any evidece to prove that how i have i setup is scientifically wrong so far bt it DOES behave better than ones setup with the cams offset the other way.

Adsport, the reason you do not hear or read about cam's exept for cams you can get of the shelf and in books out of date, is purely to do with the cam's being the heart of the engine! The cam specs used by the best etc are kept close to there chest, because it is what runs the whole show and can be hidden, so no one knows what the specs are even if they dyno it for you.
Cam's are very intresting to play with and can have the greatest performance gains of anything in the engine.
One trick with cam's you can do {much easier with rockerarms}, is to see if you can go bigger with a cam without changing the cam, by taking the clearance down for a dyno run{chev use 16 thou and you take them down to 8 thou etc}.

[Adsport]

hrm very true!

[toddw]

I was under the impression that it was the "normal" thing to do to run the larger duration camshaft on the inlet as opposed to the exhaust. Most of my reading tells me this so Adsport maybee you are on the money and didn't know it at the time.

[nick.parker]

I have heard of quite a few 4AGEs running bigger inlet cams but after getting some advice from a supercharged V8 drag racer (haha) the common thing they do is run a bigger exhaust cam profile. I also talked to a guy from Kelford Camtech who custom designed cams for the 4AGZE. Their 4AGZE cams use a larger exhaust cam too. My simulations show that bigger exhaust cams work better too.

On my car I HAD 267's inlet and exhaust. I was slightly unhappy with response so I stuck the stock inlet cam back in and got my low end bac, but mid/high was a bit weaker. I'm sure most of the low end gain was just related to getting rid of overlap..i.e. it might have worked the same if I swapped out the exhaust cam for the stock cam.

Playing around with simulated cam timing this is the best I can get comparing 240in,267exh with 267in,240exh



You can see that the sim likes the bigger cam on the exh at higher revs. I have heard that the SC'd engines benefit a fair bit more from lower exh backpressure..like any engine I guess it depends on what you're optimising.

Food for thought I guess.

[toddw]

I have heard of quite a few 4AGEs running bigger inlet cams but after getting some advice from a supercharged V8 drag racer (haha) the common thing they do is run a bigger exhaust cam profile. I also talked to a guy from Kelford Camtech who custom designed cams for the 4AGZE. Their 4AGZE cams use a larger exhaust cam too. My simulations show that bigger exhaust cams work better too.

On my car I HAD 267's inlet and exhaust. I was slightly unhappy with response so I stuck the stock inlet cam back in and got my low end bac, but mid/high was a bit weaker. I'm sure most of the low end gain was just related to getting rid of overlap..i.e. it might have worked the same if I swapped out the exhaust cam for the stock cam.

Playing around with simulated cam timing this is the best I can get comparing 240in,267exh with 267in,240exh



You can see that the sim likes the bigger cam on the exh at higher revs. I have heard that the SC'd engines benefit a fair bit more from lower exh backpressure..like any engine I guess it depends on what you're optimising.
Food for thought I guess.

Great reply Nick
With a strong NA engine do you think you would have a similar benefit. I was going to run a 288 inlet and 272 exhaust but i will try the other way around as your simulation shows. With the camshaft simulation is it possible to try the above combos either way for me to see the power gain/loss. That would be great.

thanks

todd

[30psi 4agte]

You could always try two exhaust cams of different duration . Use one as the inlet I>E larger duration and the other as the exhaust
Having the dizzy gear on both cams will allow you to swap the cams over to see which one performs better.

I.e larger duration on the exhaust or larger duration on the inlet.