I have a 94 LT1 running 13.3 right now. Its got flowmaster mufflers, vortex ram air, TPi tb airfoil, 3.75 gears, pulled front sway bar,and nitto tires. (and jet module which is worthless.) This is its current form. I want feedback on this winters plans from only experienced owners who know what they are talking about.

Plans:
-polished LT4 heads and manifold
-KBD 3" exhaust with deleted cats
-hooker 1 3/4" headers
-Granetelli high flow MAF
-52 or 58mm TB
-CC306 cam with GM Performance valve springs 1.6 rockers and all that stuff to go with that.
-Lingenfelter timing chain
-wider Nitto 555's than my current
-shift kit and performance tranny rebuild
-2800 stall converter
-30lb injectors, HF fuel pump and oil pump
-hypertech computer tuning



with this done where do you think my 1/4 mile times should be. I have a very good idea but want to see others thoughts to compare. Keep in mind this car is being built for street driving and racing. My car will be tracked for numbers but any thoughts on my plans good or bad would be appreciated. I will be running nitrous but I want numbers and stats off the bottle.

 

all I can say to you list, save the $$ on the throttle body, the 48s will move more than enough air.

Otherwise, looks good. the LT4 top end is a great start!!! port/polish, you will be rocking!

 

well the goal is all motor mid to upper 11's. Seriously do not want to stroke if I don't have to. So with the mods listed do you think mid to upper 11's from my current low 13's is about right. I ran 13.3 on stock converter leaving the line at 800 rpm's in 85 degrees with lots of humidity.

 

Mackey went 11.40's with pretty much what you are doing. I don't know his cam specs, but he did P&P heads,cam,LT headers 3000 stall and 3.73's. Currently he's running a 4400 stall with 4.10 gears and taller tires. Don't remember what his best with that combo is.

 

I have a ported/Hot cam kit 94 LT1. I've gone throught three stages with dyno pulls and drag runs on each. Most recently I had a broad band dyno pull to prove how the programming handles it. My A/F ratio is just fine with stock programing.

I pulled 310 rwhp and 13.5 on stock street tires with the cam and heads but the orginal stoccast manifolds on the car.

With TPIS headers and a custom 3" exhaust I pulled 353 rwhp, 358rwtq on the dyno and a best of 12.51 so far with DRs (on a very cold day). I turn high 12.5s to 12.7s on hot humid days this summer. I think it's got a 12.4 in it in good air now that I know how to launch with these tires.

Based on actual results plus advice from the dyno tuner John Sealock I would pare down the list.

Forget the aftermarket MAF (advice of the tuner).

Forget the hypertech tuning for A/F or timing, get it done right by a dyno tuner using LT1 edit and a broadband probe. Based on track results the hypertech would not give you anything. You can use the hypertech to alter the fan settings and boost your rev limit. A tuner with LT1 Edit can do a better job on fan settings than the selections you get with Hypertech. John lowered the temp for my high speed fan, as I complained about the car falling off on back-to-back runs even though the temp reading was only 195.

I haven't gone with the larger throttle body yet but plan to do that after the Skyline Drive cruise next Saturday. I'm going with Dave Koldos bored to 52mm and rebuilt deal on my stock TB. John says forget a BBK it's junk.

I just replaced the AC R44TLS copper plugs with NGK TR6 plugs this week. The car is back to breaking the tires loose in third gear. I think some of my problem with it falling off on back-to-back runs was plugs that are the wrong heat range. Forget about Platinum plugs in a modded engine (per John).

You have more potential than me with the LT4 heads and intake. If you get them ported before assembly you could end up with 380-400 rwhp and be breaking into the high 11s after a proper tune.

 

Heres some more advice:

Have a pro-head porter to do the heads. a few would be: Advanced Induction, Total Engine Air Flow, Pete at CNC Heads.

A Comp Cams 306 cam is a decent cam but it makes Hp in the upper RPMs and drivability and fuel milage will suffer, something slightly milder maybe a better option depending on what you want to do with the car, if you're planning on 75% strip and 25% street then that cam will be fine., However if you want just the opposite something in the 224 to 230 degree range would offer better street manners.

Forget about the HyperCrap tuning, they are totally worthless especially with a cam you are talking about. Get a competent dyno tune from someone like Ed Wright or me

Don't bother with getting a LPE timing chain, you are buying their name. Get a Cloyes LT1 1/2' single roller chain replacement or the GM LT4 extreme timing set.

For springs, I don't think GM offers any springs that would work directly with that 306 cam. Your head porter would be able to choose the correct springs and machine the heads for correct installation of the springs.

Hooker headers are ok, but a better header are the Exotic Muscle or the TPIS headers, the EM headers would be my first choice over the TPIS.

Don't bother with the GMS MAF sensor. You may actually LOOSE power with one of them POS sensors. I have advised countless people about a aftermarket sensor. The reason being is that the GM PCM has an internal MAF calibration table that matches the GM sensors. WHO knows what the actual calibration of a GMS sensor is. Their sensor maybe off by a considerable amount and if that happens the PCM will have to compensate its fuel trims for what the GMS MAF is telling it. If the PCM pegs at either the low or the high end of its limits then it can't correct anymore, and that can either cause a very rich or a worse case scenario a very lean condition. And I don't think I have to tell you what happens in case that your engine goes lean...... Use the GM MAF, with your mods as listed there is no need for a different sensor. Save your money and use it on your port work.

Thats my two bits

 

I can tell you this much, it's going to be loud! I went with EM longtubes into 3" pipe to a Dr. Gas X-pipe and then 3" to my existing PE catback. I'm starting to think I may be losing hearing in my right ear...

The 306 will be big time lopey unless you get a perfect tune. I had the opportunity to hear a 383 with a 306 before a tune and I didn't like it.

Your choice of going with LT4 heads is a good one.

Another option you have is to go to a Mez electric water pump and go right to a Cloyes true double roller timing chain.

The times in my sig are running with a crap tune and bad track conditions. I've been too busy to make it to the track since that run, but I'm hoping that I'll have a few more mph and right around a 12.4 with the new tune.

Good luck and keep us posted!

 

I say put that sway bar back on right now...

 

I agree dont worry about the MAF, I still one my stocker with the screens removed. I have a similar combo in my M6. Mods in sig. I am waiting on an exhaust system to be fabbed and I just fixed ( i think ) my lean condition with a new walbro pump. (old one was failing) Soon I will go back to the dyno and I feel its going to put down over 400 rwhp. My cam is basically like the GM847 cam. Good luck! Keep us posted.

 

well the sway bar picked me up a tenth and the driveability and cornering is still awesome so I'll leave that out for better weight transfer off the line. As for the heads I plan to have them polished up and smoothed out some but I don't think I'll be porting them anymore than they are or very little. If the hotcam springs wont work with the CC306 than what springs should I go with. I am having everything installed proffesionally and properly tuned by well know engine builders and tuners. The reason I like the comp cam 306 is that its top end. Right now with my nitto tires running low 13's I barely bark the tires leaving the line on the street in many cases I have no spin. I think adding to much low rpm power will make me sacrfice my off the line traction when I'm handing TSI AWD talons asses to them off the line and downrange. I launched last night against a TSI Talon with a 16G turbo and had more bight of the line than he did. I recommend Nitto 555's to anybody wanting street traction. My stock tires would break lose mostly through second before. So traction is a key factor because I do like 95% street racing to 5% track racing. I don't plan on my vette being a daily driver thats what my 3000GT is for, but I'd like to know I can travel decent distances reliably with it. How much HP can be expected from a CC306 tuned in right.

 

A lot and I mean a lot depends on your other parts that makes the cam work in unison with to make the BIG numbers. While you have a good choice in heads, and you want a big top end. My recommendation is that you PORT the heads as I recommended earlier. A 306 cam gives great performance from 2500 up to 6500+ but it needs the air flow to give you that performance. Its like you got a 4" pipe thats capable of flowing hundreds of gallons of water per minute, but you choked it off with a 1.5" nozzle on the end. Using that as an example you probably know what I mean now. Hp is in a direct porportional relationship to air flow. More air = power......

LT4 springs will not work with that cam, they are rated for a measly .525" lift. Comp recommends their 987 springs, or as an alternative you can use their new bee hive style LS6 springs in place of the the 987 springs. The bee hive springs may not require machinging of the spring pockets to allow installation, but I can't confirm that. You will need new retainers and also spring cups which Comp can supply to make the installation as the OD at the bottom of the spring is slightly smaller in diameter than the LT4 springs.

As for power, properly tune and with ported heads, intake and the 306 cam should give you numbers in the 450+ ranges at the flywheel. If you want even more power use the GM 847 cam. It has better lobe profiles than the OLD 306 cam. That 306 cam has been around for a long time, its a favorite cam of the F body crowd. Also another cam is a Comp NX288 grind with 238/248 duration if I remember right. That would be a good top end cam as well. In fact I have a brand new one sitting on the shelf for sale

 

The bee hive springs are great new retainers keepers and push rods are in order .
they gave me .30 seconds in the 1/4.
I can tell you the roller lifters are having a hard time pumping up.
I use the hypertech to set the rev limiter to the max and the 160 stat rear tires set and trans shift points,turns tuning.
The engine tuning will make the car slower.
I turn 13.50 in the 1/4 not a best 13.50 9 out of 10 runs.
I also use the msd 6al.
If you want to save some money just juice it use a 125 shot just after 1st gear and you will run 11.70 all day long I do.
I have a stock g44 307 rear end , 4L60E trans and have been runing juice for over a year.
My 1986 Has an lt1 with a change to lt4 intake afr heads electric water pump they only last a year.
Gen 7 computer dana 44 700r4 with shift kit and vigalante torque converter 3000 stall not run yet.
I think your engine should run 12.0 or 11.70. Depending on the tuner
the car could run alot quicker.+

 

I would check out a bigger cam and the mez pump. Call comp cams and just check what they would give you for a custom cam. Make sure you do your research.

 

Brian,
Where are you located? I am a professional cylinder head porter in Northern VA. Check out www.steadfastperformance.com, maybe I can help.
Greg

 

first off thanks everybody, you have been very informative., this site was highly recommended by some fellow track racers. Basically this is the thing. I want out of a cam very noticable power increases throughout the rpm range but still streetable. In terms of gas mileage and noise I don't care as much as reliabilty of internals. in other words if I can go 50 or 100 miles if I want with out throwing a rod through my block I'm cool with it. The hotcam I hear about a lot, How noticable will my power gains be mid and high end, while complimented by 1.6's. I turn 13.3's all day and I still have stock exhaust with flowmasters clamped to match the pipe, on a stock converter. So if I were to say put an Lt1 to Lt4 conversion in, put true 3" exhaust with no cats, headers, 3000 stall, shift kit, tranny cooler, How reliable is the car for street/weekend driving and racing, and more important what should my 1/4 miles be on a good tune.

 

Most lt4 engines run high 12's with an auto and mid to low with 6 speed.
I run nitto 315/17 but with the nos I spin them all the time,but with a dana 36 you will break the rear?don't know what you have 44 or 36.
When you break into the low 11's the rear will suffer and so will motor mounts,the mounts are over $100.00 each and their are no racing motor mounts for a vett that I have seen.
Using nos I turn low 11's and gas milage is 17 miles in the city.
A 3000 stall convert will give you about .50 in the quarter figure about 12.80's with what you turn now.
With your mods 11's should be easy if you drive the car well.
I also installed denso wide band o2 sensors only the front 2 the speed that they compute is unreal I use datamaster to check the engine and the information speed makes a diff when tuning the car don't forget to replace the o2's.

 

my rear end is a dana 36 completely rebuilt with 3.75's and about 2000 miles on it. Why would it go out. To much torque. Also the motor mounts should hold I would think. Anybody else have trouble with this or would it be fine. I really don't want to buy another rear end after just installing one if its not needed. The car just rolled to 47000 original miles. Going with an LT4 conversion kit what else would I need thats not in the kit? injectors,AFPR,fuel pump, computer program, head bolts, possibly lifters????