cat 3651 + cat springs = 8k ?

[k0mpresd]

can i safely go to 8k w/ just springs? im hitting 7500 on stock springs.

and by safely i mean, its ok if its borderline sketchy.

[mike-2ptzero]

I ran to 8k without any problems on stock valve springs. Didn't tap the top of the JE pistions till I went to 8500.

[k0mpresd]

word. 8k here we come.

[Don Supreme]

Let me know how this work out for you.

[k0mpresd]

will do. im hoping they will be here friday since he is on the east coast.

[Euro-Tuner]

I will be bringing my redline to 8k and I have been told by many people that thats the borderline/limit with the stock springs, I am seriously comtemplating going with a dual srping setup and titanium retainers, but I havent decided yet.

Mike: what cams were you running when you had the stock springs at 8k?

[k0mpresd]

he was running schricks i believe.

[Don Supreme]

Probably his Shrick cams.

[k0mpresd]

so i guess this is around the time i start hoping i put my motor together well. haha

[dougyfresh]

Is 7500-8000 safe with stock cams and springs? IE: stock valvetrain?

[k0mpresd]

not that im all knowing, but i would say the stock cams are probably the weak point in that equation.

[A4ringedONE8T]

The stock cams fall on their face past 7k, I dont really see any point in reving that high without cams

[bernB5]

i reved to 8k when I was on 034.. The 30r w/ .63 a/r really was noticably falling off up there.
once i get cams and throw a bigger hotside on i think revving will be more fun and worthwhile.

[Euro-Tuner]

so you were running a completely stock head at 8k rpm? for how long, nothing failed?

[Don Supreme]

i reved to 8k when I was on 034.. The 30r w/ .63 a/r really was noticably falling off up there.
once i get cams and throw a bigger hotside on i think revving will be more fun and worthwhile.

I think it was your cam + Im (air flow into the head) falling off and not the turbo. I feel the same thing on my 35r, with stock IM, stock small port, and stock cams...

[mike-2ptzero]

I think it was your cam + Im (air flow into the head) falling off and not the turbo. I feel the same thing on my 35r, with stock IM, stock small port, and stock cams...

Most likely mainly the cams were the flow restriction. Every little change helps increase flow at very high rpms.

he was running schricks i believe.

Correct. The schricks are the only cams I have used since I went 2 liter back in 2002. When I went to the +1mm oversize intake valves and custom intake manifold I noticed a huge difference when running past my peak hp since the power basically just leveled off with a very slight drop in power. Once I go to the larger turbo I might even start pushing it to 9k.

[Militant-Grunt]

I'm planning on building my head soon, just Mike what did you do about the rev counter? I mean ours doesn't read past 7400 or so.

[Don Supreme]

^ He installed an aftermarket TACHOMETER

[317ssayzarc]

^ He installed an aftermarket TACHOMETER

when im going to 8k i just look to see how far it is into the black and approximate lol... 9ks a whole different story tho

[mike-2ptzero]

I'm planning on building my head soon, just Mike what did you do about the rev counter? I mean ours doesn't read past 7400 or so.

If your talking about the tach, I run a Stewart Warner 8k rpm 3.5" tach. I will most likely be changing that out soon to one that reads to 9K or 10k. I really dont look at my tach till I am going into 4th gear while running the car hard at the track, all of my shifting is done by feeling when the power starts to dip.


At some point you will find that the stock tach can not keep up with the actual rpm signal of the engine in the lower gears once the engine is able to rotate at a much faster rate when making big power.

[Don Supreme]

At some point you will find that the stock tach can not keep up with the actual rpm signal of the engine in the lower gears once the engine is able to rotate at a much faster rate when making big power.

^^^ I have this issue........ sucks. This is the #1 reason I am building my head for revs. I need some room to shift in 1st and 2nd.

I kid you not, shifting @ 7200 rpm and 6400 RPM from 1st to 2nd is the difference between 12.7 and 12.1 respectively............. (Due to turbo respool going into 2nd).

[k0mpresd]

shifting at 7500 put the revs at ~5200 in the next gear. seemed perfect for the powerband. but i want insurance. and to be able to bang 8k+.

[Don Supreme]

I want to end up @ 6k when shifting to 2nd.

When i come into a gear @ 4600 RPM it takes at least half a second to respool - I know big deal right? Well you just lost .5 in the 1/4 ---- THAT IS A BIG DEAL.

[bernB5]

start flat shifting into second!
and yes, i was going to 8k on my stock AEB head as well.
I'm about to switch up the exhuast manifold and downpipe to something that flows better than the ATP.
Hopefully I'll get some cams and an intake mani soon. I'm thinking of going with the 3652's but I don't want to complete loose my low-mid range.

[A4ringedONE8T]

shifting at 7500 put the revs at ~5200 in the next gear. seemed perfect for the powerband. but i want insurance. and to be able to bang 8k+.

How did you figure that out? Just by trial and error? I lose boost between every shift, would like to know where I need to rev to in order to not have that!

[onemoremile]

Find your gear ratios and final drive in Audiworld's model library. Then plug those numbers into an online speed calculator. That gets you speed/rpm in each gear.

Bear in mind that upshifting loses some mechanical advantage so you'll have to be making more power in the next gear to keep the same rate of acceleration. That is why it is often better to hold onto a lower gear. I had a chart showing motive torque (at the wheels) in each gear which illustrated this nicely but it was for a different car. I need to do some for our cars but need dyno info that can be imported into excel to do it right.

[k0mpresd]

How did you figure that out? Just by trial and error? I lose boost between every shift, would like to know where I need to rev to in order to not have that!

uh, i went down the drag strip and watched my tach @ the same time.

[k0mpresd]

I want to end up @ 6k when shifting to 2nd.

When i come into a gear @ 4600 RPM it takes at least half a second to respool - I know big deal right? Well you just lost .5 in the 1/4 ---- THAT IS A BIG DEAL.

you need a higher limiter. better get on the phone to mike z. haha

[quattro16]

I'm setup for over 8k, but have stock cams and intake mani. So I'll be waiting for Someone to produce numbers with a proven intake mani. Then get it and cams!

[k0mpresd]

cams will produce #'s

[mike-2ptzero]

I want to end up @ 6k when shifting to 2nd.

When i come into a gear @ 4600 RPM it takes at least half a second to respool - I know big deal right? Well you just lost .5 in the 1/4 ---- THAT IS A BIG DEAL.

The 1.8t trans is still perfect for what you want and what I use it for.

Here is a rpm log of a run with the 1.8t trans and I am at over 135 mph at 7300 rpms, trap speed was 134 mph and my 60 ft was 2.4 seconds since I let the car bog off the line to keep it slower then 11.50. This is exactly why I made plans to go back to the 1.8 trans.

[k0mpresd]

so 2.8 tranny isnt the holy grail it was made out to be eh ?

[mike-2ptzero]

so 2.8 tranny isnt the holy grail it was made out to be eh ?

It is for those using it for a daily driver or those that dont have a very high rev limiter and find 1st gear way to short on the 1.8t trans.


I got about a 6-8 mph jump in trap speeds and dropped .5-.6 seconds just going from the 2.8 trans to the 1.8, this was with no other changes to the car.

[k0mpresd]

i looked in to changing the 5th gear in the 1.8t tranny to the 2.8 5th. just one of the gears was $3xx. i said no thank you.

and i want mine set to 8200. i think that will be plenty.

so why go back to 1.8t?

[mike-2ptzero]

i looked in to changing the 5th gear in the 1.8t tranny to the 2.8 5th. just one of the gears was $3xx. i said no thank you.

and i want mine set to 8200. i think that will be plenty.

so why go back to 1.8t?

To use more of the power band in 4th gear. The 2.8 trans was causing the car to feel very slow as it pulled thru 4th gear and I was only hitting the finish line at 6500 rpms while my peak hp is 7600-7800. In drag racing it is important to setup the gearing so that you hit the finish line right at your peak hp.

[Don Supreme]

start flat shifting into second!
and yes, i was going to 8k on my stock AEB head as well.
I'm about to switch up the exhuast manifold and downpipe to something that flows better than the ATP.
Hopefully I'll get some cams and an intake mani soon. I'm thinking of going with the 3652's but I don't want to complete loose my low-mid range.

Waste - there are a few people putting down 500+ awhp on that atp mani, but they have cams... get my drift?

[Don Supreme]

you need a higher limiter. better get on the phone to mike z. haha

He just got back from vacation. I tried to contact him before, but as I said he was on vacation.

I didn't want a higher limiter than 7200 on the stock head anyway.

With everything I have going in the new head I am going to have it set to 8500, but only rev to 8k.

[Don Supreme]

The 1.8t trans is still perfect for what you want and what I use it for.

Here is a rpm log of a run with the 1.8t trans and I am at over 135 mph at 7300 rpms, trap speed was 134 mph and my 60 ft was 2.4 seconds since I let the car bog off the line to keep it slower then 11.50. This is exactly why I made plans to go back to the 1.8 trans.

I am not happy ---

You shifted @ ~ 8500 and only ended up @ 5300 RPM in 2nd --- thats cutting it too close for me - with no shift light I am probably still going to hit the 8500 limiter!

[k0mpresd]

^ that does seem kind of low.

i swear i saw 5200 on the tach after i shifted. and that was only dropping from 7500. that was probably a 2nd>3rd shift though.

[mike-2ptzero]

^ that does seem kind of low.

i swear i saw 5200 on the tach after i shifted. and that was only dropping from 7500. that was probably a 2nd>3rd shift though.

My guess is that it was 3rd to 4th gear and the numbers show exactly that.

1.8t trans shifting at 7500


1st gear at 7500 rpm = 36.6 mph
2nd gear 36.6 mph = 4300+ rpm

2nd gear at 7500 rpm = 63.5 mph
3rd gear at 63.5 mph = 4900+ rpm

3rd gear at 7500 rpm = 96.8 mph
4th gear at 96.8 mph = 5390 rpm





2.8 trans shifting at 7500

1st gear at 7500 rpm = 39.5 mph
2nd gear at 39.5 mph = 4150 rpm

2nd gear at 7500 rpm = 71.1 mph
3rd gear at 71.1 mph = 5000+ rpm

3rd gear at 7500 rpm = 106.4 mph
4th gear at 106.4 mph = 5450 rpm


There is also the issue of the tach not being able to keep up with the actual rpm signal which will cause it to have a wrong reading till it can catch up. My graph is my LM1 logging it directly from the SEM.