I think I have read where this was done before with negative results. The limiting factor on my motor is the runner length. When using performance trends Engine Analyzer, that is the one thing that makes the msot difference. If I grind the divider out 3", it greatly increases my powerband.
Thks.

 

If you can get an extra set of runners ,you can cut open the sides and get rid of about 2-4" of runner length have a porter shape up the inside and then weld a peice of aluminum back on . This will definetly improve top end performance. I will be trying this soon on my friends Vette so I will let ya know! I choose to use a single plane EFI conversion on my 383 Vette which is the best of both worlds when compared to SR(to long) or Mini-ram LT1 intakes(too short).

 

I believe Ralph tried this and lost power but I can't remember for sure.

 

Keep in mind we are trying to modify an intake to do something it was not intended to do(top-end power).If you don't cam the engine for this modification you will see very little if any hp gains.The Lingenfelter 219 cam is great but it's designed for the SR runner length not a shorter runner (low speed power). Remember this modification is only for those who don't have the money or time (samething) to get the right intake for the intended purpose to begin with. I will soon be able to get hp and flow differences with this runner modification, I will let ya know!

 

I have both the time and the money to do what I want. I had the short runner Miniram intake and I hated it. The single plane manifolds that are converted to EFI look goofy to me so I won't consider it. I want to try different things and break out of this SR/219 combo mold, still retain emission compliance, still have gobs of mid range torque and still retain stock like driving manners. I'll be very interested in your results.

 

Just rub it in! Just kidding...
But with saying that, why not just go for a custom Hogans style manifold? Designed how you want, and oh so sexy looking... And if you can somehow adapt BMW's variable intake runner length system into it then you've got the best of all worlds... But if you do that, PLEASE share, its been a dream of mine for years :p:

Matt

 

Those Hogans are nice manifolds but my intention is to do something with what I have. I want to find a different way of doing things that will benefit other members also. To me that is the purpose of this Forum.

Jason

 

Sorry if I offended anyone when I said this modification was for less fortunate people like myself. Usually the fact that we don't have all the money or time to spend on our cars is what makes this fun and makes us creative. Lingenfelter makes 585hp and 585ftlbs of torque with a Super Ram on a 406 all below 6000rpm! He does it with 18deg bowtie heads(250cc INT port), a modified lower base (for the raised port among other things), and 1.8 jessel roller rocker shaft. He says lots of porting was done to the plenum, runners, and base. .600-.700" lift and duration was kept short. I had a chance to pick his brain a little at an Import event recently. Duration determines @ what point your engine will operate the best. His duration is short compared to most 406's making this kind of power, about 238-242@.050 (GOOD FOR 3000-6000 ON A 406) with a mechanical roller, which is actually smaller when compared to a hyd roller. The trick must be in the head FLOW-intake FLOW-and lots of lift to make use of all the FLOW!
If you have a flow sheet of your heads you'd probably want to open the valve .010 past max head flow (you can never open a valve too much most engine builders and custom cam simulators will suggest the most lift physically possible) port your intake, maybe shorten the runners, you can run another point of compression 11.8:1 with a good cooling system, precise tuning, engine coatings and evans coolant. You can have Ultradyne make you a custom grind cam, they have aggressive ramps that are pretty streetable, duration for about 6000rpm max with about 112LC max (gotta be careful with reversion and cylinder pressure to run pump gas). This would be maximizing your current set-up which is already pretty darn good! All these modifications will make your car a little less streetable! But the definition of streetable varies between gearheads. I'm just dreaming with your set-up, but it's what I would like to see you do or at least what ever is feasible. Let me know what you think? Hope it helps you decide!

 

Juan, you did not offend me at all. Please do not feel that way. Do you have any pictures of the cut down runners? I do not have any flow numbers for my heads other than the data that is on the AFR website. What duration would be good for a 396 that made peak power at 5500?

 

89 vette, I'm gonna try to get my friends Vette and remove the lid so I can send you a picture of the runners. Anyway it looks like you have a real nice set of heads (about as small as you'd wanna go with a 396) but still good .I'd
leave it alone but if your gonna pull the heads try to get more from the exhaust ports. Use a cam with 230-234 int dur @.050 and exhaust of 236-240 exh dur @ .050 with 112 lc this will put you @ about 5500-6000rpm peak power but it will cost you some bottom end mostly below 3000rpm so gear and add convertor accordingly try locking convertor up in third gear. I'd use split pattern cam because your exhaust only flows 72% of int you'd need to be closer to 80% before considering single pattern. Open valve .575-.625" on the int and .550-600" exh via rocker arms. If you need to use 1.7-1.8 ratio consider duration before purchasing cam. We made 500rwftlbs of torque with 232 int duration @ 3200rpm on a 406.

 

Thanks Juan. I'd appreciate that alot. I want to stay smog legal also. That 500 lbft of torque was that wit an auto? It seems autos make a lot of torque real early. That seems awful high. What heads does your buddies Vette have?

Jason

 

Yes I forgot to mention that all that torque was partly due to the convertor 10" 2800 stall auto th400. He's got afr 190cc heads mild porting not as good as yours 232-238 cam with .540-.540". 36lbs injectors.

 

Hey '89, does Juan's (12:13pm) cam recommendation sound familiar???

Juan, just curious as to how you came up with that cam spec recommendation? PS. Do you still want to do the wheels? I have not gotten anything from "escrow".


[Modified by h rocks, 10:37 PM 1/8/2003]

 

Hey89vette,

Sounds like you may be going into slighly uncharted waters.

I just received my SuperRam and I will be porting the plennum to the gasket. The Runners are already matched.

If you get pictures on porting the runners, can you send them my way?

Thanks,
Jim

 

The guy I had look at my set up came up with a cam that is very interesting and goes against the grain of almost all cams out there. This is my cup of tea. I love to do things different and see what I come up with. His design uses two different lobe types from Crane. The intake has 230 degrees duration at .050" and the exhaust has 220 degrees duration. This is opposite of my current cam. http://www.iskycams.com/techtips.html#2003 http://www.iskycams.com/techtips.html#2004 Read these two tech tips from Isky cams and it makes sense to me. The Intake is the restriction on my motor not the exhaust. Sure the Intake port can flow more air than the exhaust port, but with the intake system in place (base, runners, plenum and TB) it restricts it. My exhaust on the other hand is very free flowing with a good Exhaust port, good equal length 1 3/4" headers, free flowing cats and a free flowing cat back exhaust. This guy studies and models the flow of gas through the motor. His cam has less overlap than my current cam also. His model also shows no adverse affect of saimesing the runners 1.5" down to yield a 19.5" runner length and it actually shows a 54HP difference than my current cam at 6000 RPM with virtually no loss of low and midrange torque.

The things that strikes me as very interesting in the Isky Tech article is where it talks about over scavenging the exhaust port when exhaust duration is too long. It says your headers will glow cherry red. My headers do this and I know its not a lean condition. Its the exhaust port being over scavenged and fuel burning in the header tube. Maybe this would account for my seemingly very high header temps.

Anyway, I think I'm going to do it. I am researching this with a friend of mine who is building a 434 with a Super Ram.

Jason



[Modified by 89vette, 8:47 AM 1/9/2003]

 

I 've heard plenty of times what the other guy mentioned about more intake duration than exhaust, which would be going against the grain. A good friend of mine is gonna try it based on the same theory you mentioned, I never tried it,but once he does I'll let ya know the results. If anyone has tried it please let me know your results. H rocks I just had my first child and I'm trying to catch up on everything, anyway I still want the wheels just hoping you still have them in a week or two tops. My cam choices are based on many engines I've built for friends and myself, also being around machine shops and engine builders ever since high school helps. Soon it will be what I'll be doing for a living for myself finally.

 

No problem Juan. As long as I know you are going to take them, I won't "^^^" my ad. :-)

Is your buddy going to the longer intake duration on a SR motor? Very interesting.