Do I need more gear for my setup?
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
I'm not so sure you should have much "cam surge". I've run a similar cam but with a different trans and didn't have any surge. My friend ran a 230-236. Only time we noticed surge was when he slowed way down in first gear to go over speed bumps. If he didn't push in the clutch, then it would buck a bit. I do believe he was running a deeper gear though. That's been a while ago and many gear changes as well.
Thread Starter
Melting Slicks
Joined: Nov 2013
Posts: 2,264
Likes: 3
From: Orchard Park NY
I had to cancel the tune session due to a family vacation and never rescheduled
Look at your trap speed and dyno data. Select a gear/tire combination that will reach or exceed the hp peak at the expected trap speed in 4th gear.
Assuming you will trap in the vicinity of 107-110 mph with a 4500 rpm hp peak now (due to LTR intake), 3.07s should be about perfect with an 800-811 rev/mile tire.
If the car is slower, or if hp peak is greater than my assumption, you may benefit from a little more gear.
Cam surge will be worse with more gear.
Assuming you will trap in the vicinity of 107-110 mph with a 4500 rpm hp peak now (due to LTR intake), 3.07s should be about perfect with an 800-811 rev/mile tire.
If the car is slower, or if hp peak is greater than my assumption, you may benefit from a little more gear.
Cam surge will be worse with more gear.
I'm not so sure you should have much "cam surge". I've run a similar cam but with a different trans and didn't have any surge. My friend ran a 230-236. Only time we noticed surge was when he slowed way down in first gear to go over speed bumps. If he didn't push in the clutch, then it would buck a bit. I do believe he was running a deeper gear though. That's been a while ago and many gear changes as well.
Melting Slicks
Joined: Apr 2007
Posts: 2,616
Likes: 111
If you are still running the TPI intake and runners, your 3.08 (which is what I think you actually have rather than 3.07) gears are ideal; even with that cam you are not "pulling like a banshee" past 4500 RPM; it might "feel like it" but it's not. That dyno session will confirm it; you will see your torque fall off quick after 4000RPM and HP will soon follow around 4500-4700 RPM. Ported will help, but the system is designed for torque, not hp.
Keep your 3.08 gears unless you change to a different intake.
Keep your 3.08 gears unless you change to a different intake.
Last edited by 856SPEED; Nov 30, 2014 at 05:49 PM.
Thread Starter
Melting Slicks
Joined: Nov 2013
Posts: 2,264
Likes: 3
From: Orchard Park NY
If you are still running the TPI intake and runners, your 3.08 (which is what I think you actually have rather than 3.07) gears are ideal; even with that cam you are not "pulling like a banshee" past 4500 RPM; it might "feel like it" but it's not. That dyno session will confirm it; you will see your torque fall off quick after 4000RPM and HP will soon follow around 4500-4700 RPM. Ported will help, but the system is designed for torque, not hp.
Keep your 3.08 gears unless you change to a different intake.
Keep your 3.08 gears unless you change to a different intake.
So my question is why do you say w/ stock TPI to keep stock gears, but w/ better intake get different gears???
Melting Slicks
Joined: Oct 2000
Posts: 2,158
Likes: 9
From: N.E. WA
Never heard of 3.08's stock in the l98 c4 only 3.07's? With the cam and heads I absolutely do not believe for one split second that my power is dropping off at 4500 rpm's. Agreed a dyno session would clear that up... but the tach is still climbing at 5500 rpms faster than it does below 3,000 rpms.
So my question is why do you say w/ stock TPI to keep stock gears, but w/ better intake get different gears???
So my question is why do you say w/ stock TPI to keep stock gears, but w/ better intake get different gears???
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Team Owner
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From: altered state
St. Jude Donor '05
Tach may be climbing above 5k but power is dropping off
You need a stickier tire not so much a wider one. A wide low profile street tire will still give you traction issues. You could drop almost a second off your 60' and see a huge difference in your time slip car would be funner to drive.
You need a stickier tire not so much a wider one. A wide low profile street tire will still give you traction issues. You could drop almost a second off your 60' and see a huge difference in your time slip car would be funner to drive.
Thread Starter
Melting Slicks
Joined: Nov 2013
Posts: 2,264
Likes: 3
From: Orchard Park NY
Tach may be climbing above 5k but power is dropping off
You need a stickier tire not so much a wider one. A wide low profile street tire will still give you traction issues. You could drop almost a second off your 60' and see a huge difference in your time slip car would be funner to drive.
You need a stickier tire not so much a wider one. A wide low profile street tire will still give you traction issues. You could drop almost a second off your 60' and see a huge difference in your time slip car would be funner to drive.
Melting Slicks
Joined: Feb 2014
Posts: 2,409
Likes: 44
From: NC
Buy some new tires. You'll be amazed and in complete shock at how much faster your car is going to be. Even if those 27 year old tires, were some how brand new, the tech used to make them, is pathetic by modern tire standards. Even economy tires probably grip as good or better as your tires did new in the 1980s aside from their speed rating.
A good set of modern summer rubber, you'll pick up a crap ton of time.
Don't bother changing your gears yet.
Why on earth would you even consider getting new gears or further, when you're giving it all up at the tires in the first place?
I get it tires aren't cheap. But do it right or don't drive the car. If your rubber is over 5 years old imo, it's time to replace them. REGARDLESS of their treadwear.
A good set of modern summer rubber, you'll pick up a crap ton of time.
Don't bother changing your gears yet.
Why on earth would you even consider getting new gears or further, when you're giving it all up at the tires in the first place?
I get it tires aren't cheap. But do it right or don't drive the car. If your rubber is over 5 years old imo, it's time to replace them. REGARDLESS of their treadwear.
Last edited by MavsAK; Nov 30, 2014 at 08:41 PM.
Melting Slicks
Joined: Apr 2007
Posts: 2,616
Likes: 111
yes, you do have a 3.07 ratio; my original in the 85 was a 3.08, my bad.
But as mentioned, you can't use your tach to gauge power levels by how fast the needle sweeps past 4500 RPM, trust me on that one.
I had the Edelbrock intake and runners before I switched to the miniram; it felt just a fast through the RPM range (with the same exact engine; no changes or even a change to the tune). But the dyno results and track results were night and day......see my mods listed below.....
when I ran the Edelbrock base and runners my RWHP maxed at 296rwhp and 380rwtrq; torque fell off dramatically at 4,000 RPM and power dropping like a lead balloon after 4500 RPM.
The miniram brought me up to roughly 350 rwhp (depending on what dyno) and 343rwtrq (depending on dyno); max power after the tune was at 6,000 RPM
1/4 mile trap speed improved from 108 to 112 ; BEFORE ANY TUNE;
same cam, heads, etc. ; just changed intakes from Edlebrock base/runners to miniram.
You want gears to keep you in your max power range- higher gears will put you in higher RPM levels past your peak power levels. 3.07 gears are great for a TPI car.
But as mentioned, you can't use your tach to gauge power levels by how fast the needle sweeps past 4500 RPM, trust me on that one.
I had the Edelbrock intake and runners before I switched to the miniram; it felt just a fast through the RPM range (with the same exact engine; no changes or even a change to the tune). But the dyno results and track results were night and day......see my mods listed below.....
when I ran the Edelbrock base and runners my RWHP maxed at 296rwhp and 380rwtrq; torque fell off dramatically at 4,000 RPM and power dropping like a lead balloon after 4500 RPM.
The miniram brought me up to roughly 350 rwhp (depending on what dyno) and 343rwtrq (depending on dyno); max power after the tune was at 6,000 RPM
1/4 mile trap speed improved from 108 to 112 ; BEFORE ANY TUNE;
same cam, heads, etc. ; just changed intakes from Edlebrock base/runners to miniram.
You want gears to keep you in your max power range- higher gears will put you in higher RPM levels past your peak power levels. 3.07 gears are great for a TPI car.
Thread Starter
Melting Slicks
Joined: Nov 2013
Posts: 2,264
Likes: 3
From: Orchard Park NY
yes, you do have a 3.07 ratio; my original in the 85 was a 3.08, my bad.
But as mentioned, you can't use your tach to gauge power levels by how fast the needle sweeps past 4500 RPM, trust me on that one.
I had the Edelbrock intake and runners before I switched to the miniram; it felt just a fast through the RPM range (with the same exact engine; no changes or even a change to the tune). But the dyno results and track results were night and day......see my mods listed below.....
when I ran the Edelbrock base and runners my RWHP maxed at 296rwhp and 380rwtrq; torque fell off dramatically at 4,000 RPM and power dropping like a lead balloon after 4500 RPM.
The miniram brought me up to roughly 350 rwhp (depending on what dyno) and 343rwtrq (depending on dyno); max power after the tune was at 6,000 RPM
1/4 mile trap speed improved from 108 to 112 ; BEFORE ANY TUNE;
same cam, heads, etc. ; just changed intakes from Edlebrock base/runners to miniram.
You want gears to keep you in your max power range- higher gears will put you in higher RPM levels past your peak power levels. 3.07 gears are great for a TPI car.
But as mentioned, you can't use your tach to gauge power levels by how fast the needle sweeps past 4500 RPM, trust me on that one.
I had the Edelbrock intake and runners before I switched to the miniram; it felt just a fast through the RPM range (with the same exact engine; no changes or even a change to the tune). But the dyno results and track results were night and day......see my mods listed below.....
when I ran the Edelbrock base and runners my RWHP maxed at 296rwhp and 380rwtrq; torque fell off dramatically at 4,000 RPM and power dropping like a lead balloon after 4500 RPM.
The miniram brought me up to roughly 350 rwhp (depending on what dyno) and 343rwtrq (depending on dyno); max power after the tune was at 6,000 RPM
1/4 mile trap speed improved from 108 to 112 ; BEFORE ANY TUNE;
same cam, heads, etc. ; just changed intakes from Edlebrock base/runners to miniram.
You want gears to keep you in your max power range- higher gears will put you in higher RPM levels past your peak power levels. 3.07 gears are great for a TPI car.
The only reason I hesitate on 5k shift points is, the car doesn't wake up what-so-ever until 3k rpms... shifting at 5k is gonna put me below that 3k power band I feel.
Last edited by volkswagens-for-life; Nov 30, 2014 at 11:15 PM.
Melting Slicks
Joined: Feb 2014
Posts: 2,409
Likes: 44
From: NC
I'd stick with the stock size for this go around.
You're going to notice a world of difference, even if you went with ultra high performance all season rubber.
If you do go ultra performance all season, I recommend General Tire Gmaxs based on my personal experience, as well as Continental Extreme Contact DWS (recommend this one more).
Summer rubber, Conti Extreme Contact are amazing tires for the money spent. Then of course there's the big buck tires like the Michelin Pilot Super Sports, or Cup tires if your wallet is big enough, the traction is definitely there in spades with those.
Thread Starter
Melting Slicks
Joined: Nov 2013
Posts: 2,264
Likes: 3
From: Orchard Park NY
My stock size are 255/50/16's... was thinking about going to a 275-ish tire though. I've had great look w/ the conti DWS on other cars, but I haven't found them in a size that will fit my stock wheels and i'm NOT upgrading the stock wheels anytime soon.
I'm so damn tempted to take my car for a spin and keep the rpm's at 5k just to see how it reacts compared to 6k + shift points. Ugggg.
I'm so damn tempted to take my car for a spin and keep the rpm's at 5k just to see how it reacts compared to 6k + shift points. Ugggg.
Melting Slicks
Joined: Feb 2014
Posts: 2,409
Likes: 44
From: NC
But that's with something like an AFR 220 head on it, which has a completely obscene flowrate.
Peak will always happen below 5k.
That's also assuming you have the edelbrock base, and at least edelbrock grade intake runners (they're better than the SLP runners.) and a ported plenum to go with it all.
The stocker even ported is never going to really get that much breath.
Here's a vid of the fastest TPI I've ever heard tale of with LTRs and NA. Notice how low he's shifting.
You can hear it. He's shifting right in the 4500 to 5,000 range.
As far as your tires go, even a new set of 255/50s ought to do you well compared to the junk you have on right now. I'd consider looking around for some wheels that can go to 275/40s though at the least. Should be pretty cheap to find given that alot of guys are going up to 315s these days on C4s it seems.
I'd have gone up that far myself, save I couldn't get the exact wheel I wanted in that width.
Last edited by MavsAK; Dec 2, 2014 at 12:05 AM.