Hey all,

 

I have a problem... well, it can be viewed as a good thing if you like!

 

My car is an AE82 twincam hatch running a 20valve bottom end with a std bigport head and efi setup... before you say it shouldnt work, it does and is fantastic to drive!

After the engine swap, I have to say I was a little disapointed with the performance. But now it going crazy... The car used to hesitate when you hit the accelerator and then would slowly get going (well, not that slow) until the tvis point where it would go like a rocket. Now it revs freely and has much crisper acceleration and the induction noise is wild! I'm running a pod so it was great before but now I can't hear the exhaust over it when you boot it.

When you stomp on it in first it at approx 3grand it spins the front wheels to redline, didnt do that before.

Also, it had a noise that sounds like detonation... But I'm not sure. I'm putting some octane booster in tonight to see if that helps.

 

My question is, has anyone had problems with there engine doing this... if you can call it a problem?

 

I hope I havent waffled on to much, just a bit shocked as it was fine friday and after not driving it all weekend its doing this now?

 

Cheers,

Jarrad

hey,

 

I just recently had my engine replaced, and as with you, just after it was running beautifully, however after the first, say 3000k's it REALLY started to fly. I spoke to the mechanics and asked why I now have more power and they said, just wait til you get to about 5000, you'll have even more! They said it was all the components bedding in and settling.

 

Although, mine didn't have the detonation sound....

 

Lesley :)

I don't think his engine was rebuilt? It doesn't say so in the post.

 

 

But the real reason is, I snuck into your yard and put a turbo on it for you. You can thank me later :)

Hey all,

 

I have a problem... well, it can be viewed as a good thing if you like!

 

My car is an AE82 twincam hatch running a 20valve bottom end with a std bigport head and efi setup... before you say it shouldnt work, it does and is fantastic to drive!After the engine swap, I have to say I was a little disapointed with the performance. But now it going crazy... The car used to hesitate when you hit the accelerator and then would slowly get going (well, not that slow) until the tvis point where it would go like a rocket. Now it revs freely and has much crisper acceleration and the induction noise is wild! I'm running a pod so it was great before but now I can't hear the exhaust over it when you boot it.

When you stomp on it in first it at approx 3grand it spins the front wheels to redline, didnt do that before.

Also, it had a noise that sounds like detonation... But I'm not sure. I'm putting some octane booster in tonight to see if that helps.

 

My question is, has anyone had problems with there engine doing this... if you can call it a problem?

 

I hope I havent waffled on to much, just a bit shocked as it was fine friday and after not driving it all weekend its doing this now?

 

Cheers,

Jarrad

 

Why wouldnt it work it is still a 4A series bottom end, You did sort out your pistons didnt you (not sure if the 5v pistons interfere with the 4v head), What ECU are you running with it?

 

IMO i think you have an exhaust leak and the rushing out of the gases is making it sound like the induction and the detonation sound would be the crackle of unburnt fuel, I am running a 4A-C exhaust on my twincam (TC exhaust fuked up, only alternative as i had it sitting there) and it was slowish to rev before 3000rpm due to backpressure but i hit a rock the other day and put a hole in the exhaust and now it revs alot faster, As for the wheelspin, I have found it to be normal to get it in the Twincam (try to drive normal in the wet).

 

There are a few more factors to look at tho, Air leaks (some CAN make the engine work better as it leans it out) and the timing belt could have jumped a tooth, Setting the 4AGE timing to the next mark will make more power but that could be where you are experiencing the detonation sound.

 

Just a few things to look at.

Cheers for the Turbo Rolla boy... You hid it so well I can't even see it!

 

Ok, Trev... Thanks for the input.

Exhaust leak could be a possibility, I have had this problem before but it was completely different to this. If you have driven a twincam with the tvis stuck open thats what it sounds like... which could well be the problem. Even when you free rev it whilst under the bonnet it sounds like this.

I am running the original bluetop computer, copes with the increase in compression really well, af ratio is still fine. Also, the pistons are the original 20valve ones... should have specified this beforehand. That is why I said don't tell me it wont work, many people have! But I'm not the only one running this setup!

 

The engine is a jap import 20valve bottom end untouched, the bigport head has been reco'd and the intake was cleaned up a while back including the tvis plate.

 

Re did the timing to 10deg as per orig specs... but mine isnt quite original so it will be hitting the dyno soon to sort it out.

 

Thanks again fot the input everyone... will let you know what I find!

Hey Jarrad easy way to check if its detonating bad is to check the plugs, and see if its melting plugs or if they are light(as leighs are with his so called exhaust)lol. it may be running a little lean. Then check for leaks of any description.

hope its sorted for the weekend.

 

stu.

Cheers for the Turbo Rolla boy... You hid it so well I can't even see it!

 

Ok, Trev... Thanks for the input.

Exhaust leak could be a possibility, I have had this problem before but it was completely different to this. If you have driven a twincam with the tvis stuck open thats what it sounds like... which could well be the problem. Even when you free rev it whilst under the bonnet it sounds like this.

I am running the original bluetop computer, copes with the increase in compression really well, af ratio is still fine. Also, the pistons are the original 20valve ones... should have specified this beforehand. That is why I said don't tell me it wont work, many people have! But I'm not the only one running this setup!

 

The engine is a jap import 20valve bottom end untouched, the bigport head has been reco'd and the intake was cleaned up a while back including the tvis plate.

 

Re did the timing to 10deg as per orig specs... but mine isnt quite original so it will be hitting the dyno soon to sort it out.

 

Thanks again fot the input everyone... will let you know what I find!

 

I will do some research and see if you have bent/damaged a valve as the pistons have indents for a reason, Yes i know what the tvis sounds like and if it was stuck open it wouldnt have a nice torque curve, it would be flat and a bit sluggish off the line.

Wasnt having a go at you Trev, I know you have a few twinkys so your input is greatly appreciated.

 

I know I havent bent/damaged a valve, this was one of the things that were checked during the build. There is plenty of clearence whilst the cam timing is correct, if it were to jump a tooth on the other hand it would be a very bad site. You are right, the pistons are built that way for a reason and I was very sceptical of this engine combo before I saw it first hand n Rollagurls car... it goes like a cut cat and has had no problems over the past 12 months, she even revs it to 8800 with std valve springs! Not something my engine will see.

 

The reason I say the tvis might not be working is the extra push at 4400 has gone, along with the increase in induction noise. It used to be very pronounced and now revs cleanly to redline without any flat spots.

 

Cheers again for the input,

Jarrad.

Wasnt having a go at you Trev, I know you have a few twinkys so your input is greatly appreciated.

I know I havent bent/damaged a valve, this was one of the things that were checked during the build. There is plenty of clearence whilst the cam timing is correct, if it were to jump a tooth on the other hand it would be a very bad site. You are right, the pistons are built that way for a reason and I was very sceptical of this engine combo before I saw it first hand n Rollagurls car... it goes like a cut cat and has had no problems over the past 12 months, she even revs it to 8800 with std valve springs! Not something my engine will see.

 

The reason I say the tvis might not be working is the extra push at 4400 has gone, along with the increase in induction noise. It used to be very pronounced and now revs cleanly to redline without any flat spots.

 

Cheers again for the input,

Jarrad.

 

Ha i knew that dude, I was just saying I'm with ya on how the TVIS sounds :).

Sweet, glad to hear!

 

Well, I have good news and strange news.

 

I found and fixed the problem tonight, it ended up being something unexpected. Even after checking the timing all looked good, except I realised I had stuffed up and the timing was at 20deg btdc! Thats not right! It turned out the timing belt had slipped one tooth on the crank! This advanced the ignition thus causing the detonation. Thank furk no valves were damaged in the process! Compression is fine in all cylinders.

 

The strage part is that the car went soo much harder like this, although it did lack the top end fun, low down it was unreal! Might be time for adjustable cam gears?!

 

Thanks again for all your help everyone!

 

Stu, she will be sweet for the trip/drags/dyno! can't wait!

Why wouldnt it work it is still a 4A series bottom end, You did sort out your pistons didnt you (not sure if the 5v pistons interfere with the 4v head), What ECU are you running with it?

 

IMO i think you have an exhaust leak and the rushing out of the gases is making it sound like the induction and the detonation sound would be the crackle of unburnt fuel, I am running a 4A-C exhaust on my twincam (TC exhaust fuked up, only alternative as i had it sitting there) and it was slowish to rev before 3000rpm due to backpressure but i hit a rock the other day and put a hole in the exhaust and now it revs alot faster, As for the wheelspin, I have found it to be normal to get it in the Twincam (try to drive normal in the wet).

 

There are a few more factors to look at tho, Air leaks (some CAN make the engine work better as it leans it out) and the timing belt could have jumped a tooth, Setting the 4AGE timing to the next mark will make more power but that could be where you are experiencing the detonation sound.

 

Just a few things to look at.

 

Haha good stuff, Its all in the timing :)

 

Let us know of the performance measurements.

Yes Trev, you had it in one!

 

After this I'm really liking the idea of adjustable cam gears then hit the dyno... I still can't get over how responsive it was low down! Yet a slug past 5500!

 

Anyway, as you ask Trev, I will post up 1/4 times and kw figures once there done!

 

Jarrad

Mine is doing similar I shall check these things. Why not tell me trev, you norbit. ;)

Mine is doing similar I shall check these things. Why not tell me trev, you norbit. ;)

 

Ha, You never told me it was.

Ha, You never told me it was.

 

 

;) Its always playing up big flat spots, 180k's p/tank, etc: and so on.