Adjustable Exhaust Gear

[20v4ageBT]

I have done many searches on the internet about adjustable cam gears for 20V 4age Blacktops but I couldn't really find any info on them other then lots of people trying to sell them.

Is there much of a power increase to adding an adjustable exhaust cam gear to the 20v Blacktop?

Are the any other changes that need to be made to support this mod?

[touge_ae101]

for a standard engine - no

for an engine with cams and a tunable ECU - yes.

they are more of a tuning tool than a power upgrade thing. plus you can only use in to time in the exhaust cam as the intake is VVT.

[20v4ageBT]

for a standard engine - no

for an engine with cams and a tunable ECU - yes.

they are more of a tuning tool than a power upgrade thing. plus you can only use in to time in the exhaust cam as the intake is VVT.

Cheers for that. I will just stick to getting ram tubes.

[Burning Angel]

for a standard engine - no

for an engine with cams and a tunable ECU - yes.

they are more of a tuning tool than a power upgrade thing. plus you can only use in to time in the exhaust cam as the intake is VVT.

Cheers for that. I will just stick to getting ram tubes.

Pretty much rams tubes are a waste without an tunable ecu too.

[20v4ageBT]

Pretty much rams tubes are a waste without an tunable ecu too.

So running aftermarket tubes with the intake plenum on will have no power increases

I saw on this thread on Club4ag that a guy had been testing out loads of different ram tubes and he found a 6kw gain with 35mm tubes with the plenum on.

forums.club4ag.com/zerothread?id=20764

His dyno sheet is near the bottom. However I can't confirm how legit it is.

[touge_ae101]

for ram tubes ideally you want about 80-100mm. 35mm ones might pick up a bit of top end but will have noticable losses down low. trouble is any well designed ram tubes will have a full lip on them and won't fit in the plenum.

all you need is a decent set of extractors and a 2.25inch exhaust with a decent intake system. (search BT intake there has got HEAPS of threads on this)

[QikStarlie]

adjusting the exhaust cam is a bit numb compared to the inlet. has far less effect. and as others said not much point without aftermarket ecu or near stock engine

[ch4ng]

I have a set of 33mm trumpets inside the factory plenum on my blacktop with a

decent set of extractors and a 2.25inch exhaust with a decent intake system

According to my personal butt-dyno I didn't notice too much of a loss in the low RPM range as its pretty gutless there anyways but it was much happier 5-8000RPM (over standard trumpets)

[20v4ageBT]

I have a set of 33mm trumpets inside the factory plenum on my blacktop with a

decent set of extractors and a 2.25inch exhaust with a decent intake system

According to my personal butt-dyno I didn't notice too much of a loss in the low RPM range as its pretty gutless there anyways but it was much happier 5-8000RPM (over standard trumpets)

What extractors have you got?

[RedMist]

I have a set of 33mm trumpets inside the factory plenum on my blacktop with a

decent set of extractors and a 2.25inch exhaust with a decent intake system

According to my personal butt-dyno I didn't notice too much of a loss in the low RPM range as its pretty gutless there anyways but it was much happier 5-8000RPM (over standard trumpets)

And there goes the problem with butt dyno's.
You loose mid range and the top end feels stronger simply because the transition is bigger.
A 6kw gain at the highest HP RPM will probably loose three or four times that at useable RPM.
Helmholtz resonance is better used to broaden the useable torque curve so you place it at the lower end of your useable power band.

A very high percentage of cheap mods may give you a few KW peak but will make your car slower. In fact I can't think of one that works.

I guess the question is, do you want a dyno queen or a fast car.

[20v4ageBT]

And there goes the problem with butt dyno's.
You loose mid range and the top end feels stronger simply because the transition is bigger.
A 6kw gain at the highest HP RPM will probably loose three or four times that at useable RPM.
Helmholtz resonance is better used to broaden the useable torque curve so you place it at the lower end of your useable power band.

A very high percentage of cheap mods may give you a few KW peak but will make your car slower. In fact I can't think of one that works.

I guess the question is, do you want a dyno queen or a fast car.

So what do you suggest?

[ch4ng]

RedMist: You're most likely right about that, but hey, it feels good. I have been planning to give it a test run on a dyno, back to back to see the difference between the two to see.

20v4ageBT: They are Apex 4-1 or 4-2-1 I don't recall exactly. A much bigger diameter than the standard ones thats for sure. They look similar to BZR4AGE's ones

[touge_ae101]

this is what will happen. this is 45mm trumpets vs stock trumpet in plenum (i modified it to fit the trumpets)

same peak power but less mid range made the car feel faster but really wasn't when i look at speeds i was doing around familiar bits of road etc.



in saying that i haven't gone back to factory yet cause i'm planning big cams etc which is going to see more gains from having aftermarket trumpets.

[allencr]

So what do you suggest?

Leave it alone or expect very minimal changes, perhaps even worse, from mickeymousing around with bolt on stuff. The engine is pretty good from the factory, no significant choke point/s, and needs every thing changed, intake ECU compression cams & exhaust for a noticeable improvement.
How about a lighter flywheel?

[Mr Revhead]

mid range torque > top end hp

[Dell'Orto]

Decent extractors are definitely an improvement....my Levin gained 3kw peak, and a decent midrange increase too. Lost a little at around 2500-3000rpm but who drives a 20v there anyway

[tsoob]

[RomanV]

You cant just say "Trumpets will give you power" or "they will lose you power"

Because there's a million different designs of a million different quality levels.

I've seen dynos of revised trumpets which gave a benefit across the entire rpm range.

[Bazda]

All these need is a nice big cold air intake system with a long pipe so the filter sits down near the front guard with cold air ducting. Even the stock setup is pretty good, just need to feed cold air to it and a high flow filter.

Possibly removing the cat will help also.

Not much you can really do as said before. Pretty good in its stock form and you cant get much better unless you run a programmable ecu.

[touge_ae101]

what i have learnt is that there is a big difference between a good blacktop and one that tired/runs poorly.
there are a few things you can do if you do think your engine is getting a bit long in the tooth.

- ecu water temp sensor (makes BIG difference and also got rid of my splutter)
- fuel filter
- check fuel pump clean etc (can also revise wiring to get a better power supply to it - more peace of mind than any improvements)
- check spark plugs and replace with correct ones (BKR6E11 or 10)
- run good quality oil (personally i prefer penrite)

but yeah as already said just need to do simple intake mods and a good extractor/exhaust setup and your away. can't get a lot more out of them without going to a Link etc and cams.