Irish69427

Hey guys, I will preface this new thread by thoroughly admitting I have a horsepower fetish and clearly need counseling. LOL. I'll call it 427 Hot Rod disease (Jim, thats a compliment).

Despite barely getting the bugs out of my 496 Tripower motor which I am sure many of you are aware of it has come to my attention that even with the most optimistic assumptions regarding rear wheel horsepower that this combo will not get me to a 130 MPH trap speed on street tires. That was my goal from the beginning and is what I will need to get a 10 second time slip in street trim. This is based on alot of testing on my 06 Viper and and a new one with the higher horsepower motor. I was not aware of the the amount of power train loss these oldies lose. Based on Motorheads numbers and what my initial chassis dyno runs were I think about 22-23% is going to be realistic. This is alot more than on my Viper which is something like 13-15%. Accordingly, even my 650HP gross will likely translate to 505-510 at the wheels. That will only get me 123-124 MPH trap speed under best case. I have managed mid 11's with my viper with those numbers on stock rubber and I hold the national record for a stock 03-06 in the quarter mile so there is just no way I will see a 10.99 with that trap speed on stock rubber.

So the questions is what next. I am a big believer in the the 427 hotrod theory of taking big cubes and moving the power band upscale so it can be used without just melting tires everywhere. There is so much damn torque with these big cube motors that it is a nonissue down low. With a 540-598 short deck block build getting 750+ horsepower (which is what I estimate it will need) is easy BUT it AIN'T easy with a factory tripower intake. That is the big kicker. My carbs have been heavily modified and flowed and wil deliver the CFM (were wet flowed at 1300) but what can I do to the intake to let that big cuber breath? Has anyone really modified and seen what one of these can do with some real port work, milling the plenum dividers, extrude honing the intake, etc. I know Wilson manifolds can work miracles with just about anything but looking for some real world feed back from any one who has taken this manifold to the limit.

I love my tripower and it has to stay on the motor for hood clearance if nothing else. Don't want an L88 hood. Lastly, can I get there with my current 496 without destroying all the nice street manners it has now. I figure I will need to wind this thing to 7500 or there abouts to get a horespower number in the ball park to get me to 130 MPH in the quarter which means a big cam change. All opinions are appreciated.

427Hotrod

Man....you ARE a glutton for punishment!! It just never ends!



Here's an idea of what we recently did to a factory 2x4 283/270 HP intake with WCFB carbs to install on a 400" motor. This was the first rough cuts. There was a LOT of porting that went on and we opened the plenums a good bit. Would have gone more..but it was getting to be a structural integrity issue if we went too much more.

I know lots of folks running high 6's in the 1/8th and busting through 100 MPH trap speeds there...and then running high 10's in the 1/4 with around 125-126 mph. If you recall Alan just hit a 10.99 with his 496 Hyd roller motor with 3.08's and a tight converter in his near 3800 lb C-3. His RPM air gap intake was helping some..but he did pull it off with around a 123 trap speed on drag radials and big fat front tires. His motor dyno'd at just over 650HP on two different dyno's.

I don't think you will have to twist it mega tight to do it....if you can halfway get it to hook you're there. I ran mine once with a little flat tappet and plain BFG street radials and full exhaust. Ran 11.40's@131+..but couldn't get my foot in it until 3rd gear!

JIM

TheSkunkWorks

I'll be staying tuned for your "Broke my IRS, what now?" thread.

ajrothm

Irish69427

Yeah, I know I can do it with some sticky tires, drag radials or slicks but I never run them. Then I wouldn't need that trap speed. But to make up for the poorer 60 foot and traction issues I need the extra mph for any consistency. To get the 08 viper in the 10's I had to pull a 1.8 60 foot which I have done many times in my 06. Even now with maybe 4 passes on the current car I pulled a 1.98. One of the reasons I haven't broken anything in the drive train until this motor is by making the tires the scapegoat for too much power. Lot easier to buy a new set of BFG T/A radials than the $2000 grand auto gear trans I just bought or rearend. LOL. I can probably get it done with 128 if everything clicks but looking for a little extra. I just think 123/124 with my current setup wont get it done with out traction enhancement.

I keep thinking there must be some flow to be had in this manifold by cutting the plenum divider on the secondary carbs. They are completely isolated and that limits carb cfm the motor sees as well as plenum volume. But sure would like to here from some one who has done it before i cut up a $2000 manifold.

Irish69427

Hey I have had enough bad luck on this build. Don't feed the bad luck monster. LOL.

Irish69427

Jim, did you document any power gains from this porting? What kind of cam specs would my 496 need to get me in the high 120's for mph. Heads flow 370 @ .650, current cam 245/250 @.050.

427Hotrod

No back to back testing. It wasn an all new build...but we had run that intake in stock form a 383 previously with some ported iron double hump heads. It was a TQ monster...actually did better than C5 Z06's with headers and stuff until 4500 rpm or so...then choked bad.

The intake is still the restriction...even after porting it made 495HP with the 2 WCFB's, 540 HP with a Dart dual plane and a 750 DP and 555 HP with a Weiand single plane and 750.

You're intake is starting out much better than this though. You might drop Steve...632C2...a note. He was building a sneaky 496 and was going to do a lot of dyno testing with a tall '67 intake and a short '68 one. not sure where he is on it.

I think we're going to need to be up in the 255*+ range to make it scream on the top end...and it needs to be a *good* lobe.

JIM

10caipirinhas

Guys like all of you make the pain of sitting on my cheque book easier to handle.

FRSTR90

I may be wrong here, but I think your air cleaner is one thing holding you back. I mean it is only about an inch tall. I think you will need an rpm air gap at the very least with a decent sized air cleaner..

Maybe try a run without your air cleaner and see if that changes anything..

427Hotrod

It's easy on us too...our checkbooks arer thinner!!

JIM

Irish69427

You would not know this but I tested and have modified the air cleaner setup on my tripower in another thread. Raised the carb base through a unique mod and tested it on the dyno with and without the air cleaner. With my modified version it only lost 8 HP from no air cleaner at all so that will not help.

ajrothm

Do a search for ZL1PWR's threads on his vette. I don't remember the specifics but it ran in the 10s at 130+ and it is a stick. I believe he was on skinny drag radials or something though. There are several vids of it....it's really impressive.

Also search around on the net for Wayne Nelson's old L88 and Terry Pennington' orange L88. Both of those cars run in the F.A.S.T. Classes, run well into the 10s at 130+....on stock Wide Oval tires...both of those are autos though...

Good luck!

Irish69427

I have followed the penningtons closely. Problem is they are running Wilson manifold's prepared intakes and single four barrels. That is the problem. If I run an L88 hood this debate is over in 5 minutes. Just a cam change, good single plain manifold and dominator carb and I am there. The trick is getting there with a tripower.

ajrothm

Yeah I can't help ya on the tri power thing... I just know you are gonna need some serious power to run 130mph * when trying to do it spinning the first 300' or more on BFGs....and it's damn sure gonna be hard to run a 10 anything with horrible front half numbers. Remember once you build all that power to trap 130+, it's just gonna be that much harder to get 1st/2nd to hook...and I am not talking about hooking on the launch, I mean 100' out when you finally ease it into 2nd gear.

I know you have done this in a Viper but....suspension, tires etc everything is different. A Viper has what a 335 tire?

The fact is, you could spend $400 for some drag radials and run high 10s at close to 130 now with the 650hp you have and still have a streetable, low maintenance engine.

I think you should go run it at the strip and see what you can get out of it now on street tires before you go into the motor again. Frankly I think you will kill too much of the track with it spinning to get any decent ET or MPH out of it. 60' and 330' are everything for a good ET.... JMOP


FWIW. I talked to a guy this weekend with a Lingenfelter C6 Z06, 605rwhp all motor, he ran it on Pilot Sport Michelin true street tires back in Feb and went a 10.80@137 so I guess it is possible to do what you want...just takes a lot of power, suspension etc...

Rmorgan&11

3 NOS Plates ??

straub18045

start with a c4 susp. conversion?

gkull

TRi-power is just a bad design. I've said it for years. The problem is they are not designed to cause a ram effect. I'm a west coast historic race car person. To improve (not cheat) some of our old intakes a California manifold flow shop actually takes your old intake maniflold and cuts them in half and turns them into a flow master piece.

When they come back it would take a trained eye with an stock manifold right next to it from the top to see theat the runners are bigger and taller. They are media blasted and after you paint them nobody, but you would know.

I would call around Florida and find a intake flow bench place.

Irish69427

Aj, you make alot of very valid points and I do intend to flog the car as is before I do anything to it. If I could get a ten with some DRs I might live with that. But I really like to run what I brung. Anybody can make a car e.t. well with no traction issues. That is half the fun for me and if Pennington can run a 10.33 on 8" bias plias at 133 it can't be that out of reach. Granted he has 4.56 gears which make a hell of a difference from a 3.08 but nonetheless it is in reach.

I'll give you a perfect example. The 08 viper run I am talking about (this wasn't me driving this one) ran the following with a stock 3.08 gear and bone stock. Weather conditions were superior with negative density altitude which gave the motor the extra it needed but here are the numbers. 1.76 60, 4.75 330, 7.14 1/8 @ 102.81 and 10.92 @129.79

A Viper is a VERY hard car to launch and 1/4 mile because of the monster torque ,etc. All the things that start to show up in a big inch vette. Granted they have more rubber but I actually find my vette easier to launch than my viper with better weight transfer and less tendency for wheel spin. With offset trailing arms, etc. (which I have) I can get a 10 inch rim under this thing and alot more rubber. And to get numbers like this you do many counterintuitive things with respect to drag racing conventional wisdom - for example - FORGET about powershifting 1-2. Waste of time. All rubber no traction. A quick shift with just the right coordination gets it all to the ground and none to very little wheel spin. But it has to be JUST right. Not going to give away all my secrets here but you get the idea.

With the above in mind I just don't think there is enough power with all the magic tricks to pull more than mid 11's even with a 1.8 60 in this car. But I could be wrong.

Irish69427

Loved this idea, but there is NO hood clearance left. Not even for a 1/2" plate under the carbs.