Went to the track again.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
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From: Capital region, NY
Went to the track again. Well I finally made it back to the track last weekend and got some current times. I have been fighting power issues as the car traps a lot lower than I have seen people with similar mods trap. I ran a 12.2@113. Hell a cam only (plus bolt ons obviously) cc306 95' Z28 on youtube ran 12.4@114. I'm launching the car fairly hard, revving to like 5k and dropping the clutch really aggressively. I'm not dumping the clutch though. The car takes off quick with no wheel spin. I pulled a 1.8-ish 60' with that run I believe. (The time slip is not right in front of me)
My mods are 232/240 .578/.574 110 LSA LE cam, brand new lunati 723925 K5 double springs, 1.6rr's, Ported heads (the flow specs I got put them in between an LE1 head and LE2), massaged intake, 52mm TB, electric WP, 30lb injectors, Long tube headers w/ duel 2.5" exhaust, 3.73 gears, t-56, SLP "Claw" intake with smooth bellows, plus I have used both Madz28's tune and I currently have been using Solomon to try to straighten the car out. The bottom end has like 12k on it with forged rods and ARP rod bolts; stock pistons, eagle crank (yeah I know, I know).
This is in my 84' Corvette.
I have not confirmed what the heads flow, that's on the docket for this winter, I want to send them in to be flow tested. I also have plans to put the car on the dyno before the end of the year.
The trap speed seems quite low for the mods. Others I have seen online with similar setups area trapping 118mph or so.
Does my trap speed look low?
My mods are 232/240 .578/.574 110 LSA LE cam, brand new lunati 723925 K5 double springs, 1.6rr's, Ported heads (the flow specs I got put them in between an LE1 head and LE2), massaged intake, 52mm TB, electric WP, 30lb injectors, Long tube headers w/ duel 2.5" exhaust, 3.73 gears, t-56, SLP "Claw" intake with smooth bellows, plus I have used both Madz28's tune and I currently have been using Solomon to try to straighten the car out. The bottom end has like 12k on it with forged rods and ARP rod bolts; stock pistons, eagle crank (yeah I know, I know).
This is in my 84' Corvette.
I have not confirmed what the heads flow, that's on the docket for this winter, I want to send them in to be flow tested. I also have plans to put the car on the dyno before the end of the year.
The trap speed seems quite low for the mods. Others I have seen online with similar setups area trapping 118mph or so.
Does my trap speed look low?
That does seem low, just for comparison, Back in the day, my 95 Z, lt4 hot (218/228, 525-525) cam, 3.42 rear gear and an auto with a 3600 stall, was running mid 12's, dont remember the trap speed.
What size tire on 3.73 gears? With that cam I think you should have a 4.10 and even higher if you're running a taller rear tire. What RPM are you crossing the traps? Where is your power peak?
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
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From: Capital region, NY
I have 275/40/17 on the back (no wheel spin), I cross the line at 6k. Little over or a little under depending on the run. I'm not sure where my peak is, hence why I need to dyno the car. Seat of the pants the power peaks at 6k-6200.
You need to gear down. You need to be crossing the traps at or just a little past your power peak. You are leaving mph on the table with that gearing. If you can, get the car dynoed so you know exactly where your peak is and then look at a gear/mph calculator. If it were my setup I'd put 4.10's if you're running those tires and probably 4.30's if you were going to go with something like a 27" Hoosier.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
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From: Capital region, NY
I really need to get this car on a dyno. Then I'll know how down on power she really is.
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Yes. Don't guess where your peak is. You can either go to the track and shift at different RPM to see where your best results are, which can be time consuming as **** if the track is crowded, or get it on a dyno and know exactly where it is, then get the gear that would compensate the best.
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On The Tree
Joined: Apr 2013
Posts: 179
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From: Utica, IL
I agree with the other guys. That cam definitely needs to be shifted at a higher RPM. Hopefully your Eagle crank is forged. Any idea what your compression ratio is?
Sounds like something is holding you back if it is falling off after 6,200.
Sounds like something is holding you back if it is falling off after 6,200.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
Not sure on compression ratio. Stock style head gaskets, stock B-body pistons, I don't think the heads have been messed with cc-wise but I can't say for sure as they are ported.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
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From: Capital region, NY
The way I view it is trap speed is the potential of your vehicle, ET is how efficiently you are using it.
Basically Trap Speed indicates Horsepower, ET had too many anomalies that could affect it like bog, tire spin, poor shifting ect. this is why sometimes you can hit say a 12.0 et with a 110 speed or a 12.5 with the same speed, because its the horsepower that is pulling you thru..
My much smaller 227/233(I think?) cam still wanted to cross the lines at ~6500. I shifted at 6300 partially because it was a stock bottom end with high miles, and (the real reason) because I couldn't get an accurate shift point with my 700r4 since it uses the ancient shitty method of springs and weights. I got it to shift at around 6300 and left it at that...but it had not slowed down yet every time I rose the shift point so I know it wanted even more.
Possible valve float issues may be cutting you off before your true power peak. Check the installed height of the springs, if installed incorrectly may not have enough seat pressure.
Possible valve float issues may be cutting you off before your true power peak. Check the installed height of the springs, if installed incorrectly may not have enough seat pressure.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
My much smaller 227/233(I think?) cam still wanted to cross the lines at ~6500. I shifted at 6300 partially because it was a stock bottom end with high miles, and (the real reason) because I couldn't get an accurate shift point with my 700r4 since it uses the ancient shitty method of springs and weights. I got it to shift at around 6300 and left it at that...but it had not slowed down yet every time I rose the shift point so I know it wanted even more.
Possible valve float issues may be cutting you off before your true power peak. Check the installed height of the springs, if installed incorrectly may not have enough seat pressure.
Possible valve float issues may be cutting you off before your true power peak. Check the installed height of the springs, if installed incorrectly may not have enough seat pressure.
Thread Starter
Launching!
Joined: Feb 2010
Posts: 296
Likes: 0
From: Capital region, NY
