Those that have been following my thread about my 396 dyno results know that I said my quest for more power was over. That lasted for about an hour! :lol: I have been going through, again, all the things with my car that would cause a peak horsepower at only 4600 RPM and staying relatively flat to about 5500 or so. I say flat because my HP at 4600 is 334 and at 5500 is about 315 HP. Beach Bum mentioned valve springs which could be a possibility. I am also wondering about ignition. I am running the stock HEI system with a Davis/Hypercrap 53000 volt coil. I would think that the stock HEI system could handle the job. Beach and Dennis. Are you running the stock HEI? What can I do to improve it?

Since I don't have a scanner, this is the best I could do with a digital camera.

Jason


[Modified by 89vette, 12:39 PM 11/5/2001]


[Modified by 89vette, 12:40 PM 11/5/2001]

 

Look at you Jason your at it again, lol....

 

While I can't really tell you if it's any good or not, I'm running the same ignition setup and I'm having similar power problems as you. My peak hp and tq numbers fall right around where your's does. Unfortunately I don't have the stock set up left to test if there is any difference.

 

Where is your peak Glenn? What are your peak HP and TQ numbers and at what RPM? Maybe we can help each other here.

 

I can't post my graph because I have neither a digital camera or a scanner.
Peak rwhp: 327.3 @ approx 4800 rpm / rwtq: 405.9 @ approx 3700 rpm

HP graph crosses 300 @ approx 4100 and stays above 300hp till about 5700 rpm.

 

Glenn

Bring the Dyno graph to Etown on Sat, I will take a digital pic for you if you want.

Let me know.

Vic

 

Glenn, that is real close to mine. If you can tell, I am above 300HP from 3700 to 5700 RPM. Some commonality I would say!

Jason

 

Vic,
I'll bring it to E-Town this Saturday.

Jason: Now what we need is for some forum members with similar setups and different ignition systems to chime in here and add there .02.

 

Jason
My ignition system is nothing special. I am running the same coil(hypertech 53,000 super volts :p:),msd6al with the stock dist.
I spin up with no problems to 7000.

Not shure with your springs. I know the biggest you can squeeze in hte AFR190's is a 1.46- for ther stock spring pockets that is. Comp makes a nice sping in this size. John(bowtie8) is running these with his 236-244 solid roller.

You need to get some track time in :yesnod: with some sticky tires of course :lol:
Dennis

 

Hi Dennis. I go back and forth on this horsepower thing. I keep thinking that a simple $50.00 part to fix something that is broken will fix my problem. I'm not sure why I'm even worried about it. The car is plenty fast for me and has lots of power. I very rarely spin it past 5000. I don't even race. Maybe I should just accept what it does and that's it. Some motors run better than others. Even if I squeeze another 40HP on the top end I probably won't even notice it that much. Remember how dissapointed I was when I first started driving the car with the Minriam? It was not that much faster SOTP than the 350 Miniram. It wasn't until I put the on Super Ram that I started feeling the big difference. The reason is because I picked up a ton of toruqe where I do most of my driving. The thing that is bothering me is the fact that my HP peaks out so low. If I was peaking 334HP at 5400 RPM instead of 4600, I'd feel alot better. I would love to know what it is. Whatever I think of you prove me wrong with your car! Don't get me wrong that's not a bad thing. It keeps me from wasting money. Something just does not add up. I'm trying to cover al the bases. Did you notice a difference with the MSD?

Jason

 

Dwell, saturation, etc. is controlled by the HEI (EST) module, not the coil. I was always under the impression that the module and not the coil was to blame for problems such as this. -Matt-

 

Any idea what the air fuel ratio was during the dyno pull? Could be something as simple as a weak fuel pump or fuel filter. :confused:

 

If you want to throw a little money at the module, I have a new Performance Distributors "hi-perf" module in an un-opened box. Fits 81-91. They accidentally sent me two of them. Got it from Eckler's and is the one that says Dyna Mod on it. Catalog: $80. asking $55. I will pay shipping. BTW, I have this one in my dist. w/ MSD cap & rotor, works great.


[Modified by 89 Paul in cal, 8:48 PM 11/5/2001]

 

i'm not sure why something like a msd 6al wouldn't be a half bad idea with a outboard blaster 2 coil. with the hei adapter kits they have i managed to rig one up pretty cheap & the car fires incredibly fast now & definaltly will cost less to change coils from now on. you could stay stock i supose but most the people i've met have all done the msd box

 

I agree you're not having coil problems; it's a simple voltage step-up and that Davis/Perf Dist/Hypertech 53kv part is about the hottest spark you can get. None of the external coils, Blaster, etc. come close (and it's almost imposible to find a mounting point in a C4).

It sounds like module problems. If you want to stay stockish and have an easy install, buy that guy's Perf Distributors module; for a more significant upgrade pick up an MSD or Jacobs multi-spark box. Like someone said above, most of us run an aftermarket ignition.

 

89vette & Glenn,

My old MSD 6A unit failed with my old 350, I've never gotten around to replacing it yet.... I have been running the bone stock ignition on my 383 always. I conducted a fairly accurate before and after test with my old 350 with MSD 6A and I picked up absolutely zero et making the move. However, at the time I did my test I was running long tube runners, thus the motor was never above 5000 rpm... I think aftermarket systems will help out the guys who are trying to spin their motor to 7000 rpm. However, considering a MSD6A is only around $ 150, I'll upgrade again sometime within the near future.

I realize both of you are probably fairly content with your 330 rwhp #'s, and that is quite a bit of hp that I am sure feels great... but, the reason you should keep looking for more power... is because its their, and probably free.

As stated in another thread, I'm making 362 rwhp... and probably another 5 on top of that nowadays. The dyno I use is not juiced up, stock LS-1 corvettes dyno at 290 rwhp on it, which is right in line with the rest of the world... therefore, knowing this, you guys without a doubt have more hidden hp in your set-ups. Keep in mind, my 383 Superram motor is not even close to optimized with iron heads that just don't flow very well ported. (They flow after porting right around what AFR 190's flow straight out of the box at 260/190) My motor was built at 9.8-1 compression, however after head porting, this could be down to around 9.5-1. My Superram base intake has not been touched, Bowtye8 who I bought my plenum and runners from did some work on them though. My point being to all of this, my HP is on the "lightside" for a 383 SR motor in my opinion.... a 383 SR motor with good aluminum heads, a compression ratio up around 11-1 and a ported Superram motor should easily exceed my #'s. I am eventually going to install some good AFR 190 or AFR 210's with some bowl work and also bump up the CR up to around 10.5-1 and port the SR base... with these modifications I would hope at least 380 rwhp would be doable and even 390 rwhp would not be out of the question in my opinion. This is with the converter unlocked.... with it locked I would expect over 400 rwhp.

You guys should be up around 370-380 rwhp in my opinion, especially 89vette with his manual transmission. Also, a SR only making its peak at 4600-4800 rpm there is something wrong !!! I made that peak with my old Accell large tube runners..... even with your cam advanced 2-4 degrees you should at least be up to 5200 rpm. My 219 cam is retarded 2 degrees which created a hp peak at 5600 rpm.... I think degreed straight up you're gonna be right around 5400 rpm give or take a 100 rpm. Find out why your hp peak is so low and I'll bet you both find between 25-50 rwhp.

Don't take your fuel system for granted..... forum member "Ralph" went to the track several months back and ran a solid 3 tenths off his average.... he thought his fp was A-okay, but upon hooking up a fp gauge to it and running some wide open throttles he discovered that fp was dramatically dropping at wot..... he replaced and his et's returned to normal. I would bet a nickel his HP peak got knocked down to below 5000 rpm when his pump was on the fritz.

I don't know why your #'s are a little bit short, but I'm sure it would be a blast trying to find the hidden HP... I enjoy challenges like that. Start dissecting and don't take anything for granted is what I've learned, just because it looks good from the outside doesn't mean its functioning perfectly... Find that Power !!! The power is their !!!!

btw, as a last note.... hit the racetrack, thats really a better dyno in my opinion.... 89vette with your excellent heads and manual transmission you should be good for 117 mph mininum in the 1/4, with your set-up even 118-120 should be doable.... anything short and you truly do have a problem, if you run 117 + then throw your dyno #'s in the garbage and just enjoy your motor !! :) Glenn you should be good for at least 115 mininum, and probably 116-118 mph with your auto.

good luck guys
Beach Bum

 

Beach, thanks for the long reply. With my motor, it seems like the most logical reason for me not making the power I should is motor is starved for air. I was thinking that Super Ram is just not flowing enough air for 396 cubes. Then I remembered that the Miniram peaked at about 5500 RPM at only 327HP. With the Miniram, one would epect with everything else being equal would make alot more HP than the Super Ram. It actually made less and at higher RPM.

I then think that MAF and stock airbox with an open lid and KN filter are not flowing enough air. But then people like you and Dennis made 360+HP sucking through the MAF's! So that is another road block.

Lets think about valvesprings. With the Miniram peaking at 5500 or so and revving freely to 6000+ would this really be a problem? Although there is no way to verify how many miles the heads have on them, there were sold to me as barely used and it looks as though they are. My heads also have the 2.08" intake valves which should further increase the top end.

Lets think exhaust. The headers are TPIS longtubes that are attached to Random bullet cats that feed into a Corsa cat back. Each 3" cat flows 530 CFM. So that doen't seem like a big restriction.

Super Ram. The runners were slightly ported and then extrude honed. The accel base is not ported but extrude honed. The runners seem as if they could use more porting in the middle. Anyone ever siamese the runners an inch or so down?

Fuel system. I'm running 30 pound injectors with a Bosch in-tank hiflow fuel pump from TPIS. So that is not a logical assumption either. Also remember my WB O2 showed a good 12.7:1 mixture at the upper end of the RPM scale indicating good fuel flow.

Ignition. Stock except for a Davis DUI coil. Same ignition setup you and Dennis are using for the most part. Also the plug wires are new MSD units. So that's most likely not the problem.

So I really have nowhere to turn except to open the air intake some and port the Super ram runners slightly more. The one thing I don't really know is how my cam is installed weather its advanced or not. Its a little on the small side but the biggest one Mike Oshuca installes on his emmissions legal 396 LT1s. There is alot to cam timing that I really don't understand but maybe there is alot more to the 219 cam that meets the eye. I mean that cam is smaller in duration than my current cam but maybe its better optimized for the Super Ram set up. Even so, I'd expect a higher peak HP that 4700 RPM.

Keep the suggestions coming. I love to hear them.

Jason

 

89vette,

I don't think there is anything wrong with your basics such as heads, superram, cam, exhaust, air intake system..... they're all good stuff.... and your 396 cubes are not too much for the maf with your set-up (Could be with the MR and 6500-7000 rpm), but not at your power level. You don't need to port anything else in the world... no major changes at all.

You need to look at the little things very, very closely.

1) Valve train geometry... are you sure its correct.

2) Are you absolutely dead positive the fuel pump is not dropping fp at wot..... flooring it in the garage is not going to give you the answer.... you gotta be on the road with a gauge taped to the windshield.

3) Ohm out your plug wires even though they look great

4) disconnect your knock sensor.... unwanted or un-needed retard will knock a lot of power out

5) Are you positive the TB opens all of the way at wot

6) Are you positive a plenum or manifold gasket didn't slide while assembly, thus blocking the intake port severely.... that'll make a head flowing 280 cfm flow 200 cfm in effect.

7) Are you absolutely positive you have the right header gasket installed... on that protrudes into the exhaust port will kill performance.

8) Any change your tranny is robbing some power... is it healthy.


I don't have a clue if any of the above is it.... but virtually anyone could be, and you have to look at each one.... I've had a mininum of 4 of the problems above at one time or another.... and had to correct all of them. And each one costs some serious power.

let me know when you finally figure it out.

later
Beach

 

Now you got me thinking. I was running low 13's pretty consistantly and then I splurged for the hypertech 53kv coil, cap & rotor and MSD wires. I also threw in a module from the local parts store. Same conditions and same track and the e.t. slowed down! Went from 13.02-13.08 to 13.28-13.42! I couldn't figure out why. Oh by the way I also dynoed and the h.p. peaked at 4500 and fell off the cliff at 4800! Coincidenc? HMM! The dyno operator said something was wrong with my car but I figured it was just the typical long runner curve thing! Still hunting for the answer!
John

 

I am most definitely not content with my motor's current output. The best I've been able to run at the track is 13.01 @107 mph. I went out and bought the Ease scantool software and was able to see that the ecm was pulling out 14 deg. of timing. On Monday, my tuner is modifying the knock sensor so it's less sensitive.

I have the stock fuel pump so it's possible it's part of the problem. I also need to mod my exhaust further. While I have the TPIS long tubes, from the catback i's still basically stock. I have spoken with Mufflex Performance exhaust and they recommended a 4 in. cat with two 3 in pipes back to flowmasters. I haven't done it yet due to budgetary constraints.