Quote: Originally Posted by Kevin91Z BINGO! Dyno Don and I keep telling him its valve float since he has 3/8" pushrods and only 115 lbs on the seat. Yep,,, probablly needs 150 - 160lbs at seat with a spring rate in the 370range,,, regular ole springs - don't know what that would convert to in the beehives.

Good luck with solving the mystery. Very strange how it peaks at 350hp and that's it.
This was more appropriate ealier on in the thread...but i'm hoping you wouldn't mind providing an opinion on the TPI plenum/intake base. I understand that it is not necesarily a good idea to powder coat the inside of a carborated intake manifold due to reduced fuel atomazation, but how about when the injector is just above the head intake runner? I know that the semi rough surface of the aluminum promote better air fuel mixtures because of the semi rough surface, (and powder coating would fill in some of the rough surface) but does this even play a role for the TPI unit, or any multi-port injection unit, since the injectors are beyond the intake base? I'm asking because i'd like to have my plenum powder coated and not have a negative impact, I suppose I could have just the outside done, but this has me curious.

All the TPI's I've had apart show (and smell of) definite signs of reversion. At the very least I would not put a totally smooth coating in the intake base itself, to allow for any fuel that drops out to be easily pulled back into suspension. It doesnt take much to do this, just dont go polishing the surface and it will be fine.

Thanks. I think i will stick to the outside. You are absolutely right, when i disassembled my TB from the plenum, I could smell fuel. gracious!

Manley has a beehive spring #221428 with a seat pressure of 150 lbs on the seat and 355 open. Rate is 341 lbs/inch. The specs say the seat pressure on the Comp Cams 26918 beehives I have now are 130 lbs. Rate is 313 lbs/inch. I'm not adverse at all to changing out the springs. I would think I would only need to change out the intake side.

I have ordered new spark plugs with resistors this time around. Hopefully that will solve the electrical problems. If so than I will put the car back on the dyno for more testing. Believe it or not but my electrical problem screwed up the Dyno Jet computer as he had to restart the program a couple of times.

You're not running resistor plugs

Hehehehehe. Well, the sparkplug wires I have are supposed to have suppression on them which they do. I know you need resistance somewhere and I thought the wires would be enough. Apparently not enough.

So maybe sometime next week after I get the plugs changed out I will put the car back on the dyno. Assuming that fixes the problem and Don can fit me in to change the number 8 plug. Then hopefully I can get a clean dyno run.

Allen, what are the cam specs that you are running on that motor? Thanks.

Its the Comp XFI268HR-113.

Yep. The details are as follows. Advertised duration is 268 intake and 276 exhaust. Duration at .050" is 218 intake and 224 exhaust. Lift is .570" on the intake and .565" on the exhaust. 113 degree LSA. Supposed to be installed on a 109 ICL but I have it on a 110 ICL.

I have run this combination on Dyno Sim and EA Pro 3.5 and they show it making peak horsepower around 5800 to 6000 rpm.

Quick update. My new resistor spark plugs came in today. I changed out the 4easy ones on the drivers side this evening just those 4 made a big difference.So that is the problem. I will have the rest changed out by this Friday. I have made arrangements for a lift to get to the harder ones.

Then I will see if I can get back on the dyno this Saturday for some good clean dyno pulls. By early next week for sure I should have some results.

You're kidding. The bucking and jerking and stuff on the dyno with the Ostrich is because of the spark plugs?? Wow!

Huh.... ??

I thought all spark plugs were resistor plugs??

Are you sure your old plugs had the correct electrode reach for your heads?

No, you can still buy non resistors. Its not a good idea on anything that runs on electronics. Maybe tomorrow he'll post up proof of that.

Yep, they were non resistor. Kevin that could well have been the problem with the Ostrich. Electronics don't like noise. I had Don change out the other 4 spark plugs on the passenger side today. My radio finally works fine without freaking out and the idle is perfect with no jumps on the tach. So looking good on that front.

I confirmed the dyno pull for tomorrow. So we will put the car back on the dyno for some clean pulls. I don't expect to much of a gain over the previous 350rwhp. I may very will have a problem with valve bounce. Tomorrow should give more insight as to what is going on.

I'm going to slacken the transmission tv cable on the dyno so that the pull can begin earlier in the rpm range without down shifting into 2nd gear.

i've heard this isnt a good idea. i asked about this before i went to dyno

i ended up just setting my torque converter unlock prevention threshold in my 6E AUJL bin to 58mph. once locked i got good readings from about 3200rpms or so on up. i was gonna try abit lower to see if locking the converter would keep it in 3rd gear even lower rpms

Its risky, but likely a run or two wont do too much damage unless you're on the verge of killing the trans anyway.

Hey I'll bet Sarkis' dyno works fine now without all that RFI in his shop from your car.

We will take the first pull up to 6000rpm and then a looksee at everything. I was thinking only for one run but maybe just not do it. I was just looking for a way to see what is going on under 4500rpm.


Yeah that RFI was screwing up more than my car. I wonder how much it was affecting the dyno readings? Find out tomorrow.

There is a group purchase on the Corvette forum for the first intake system. I was wondering what you guys think would be max rpm on a modded 350 with this system?

What is being done to the First Intake System? Is it going to be bolted on as it comes out of the box or are they going to clean it up some?

Remember it is still a long runner system as it comes from First but higher flowing. The First has boatloads of potential but it needs working over for higher rpm output. BadSS probably has the most knowledge on this and maybe he will post up.

Thanks Trans Am 89, I plan on porting the first system for more flow. Right now I have Arizona Speed and Marine runners and a ported Edlebrock high flow base and was wondering if the first would flow more? Hopefully Bad SS will chime in.
Thanks,
Steve

with a good custom grind cam, you'll beable to make ALOT of power under the curve with the FIRST from what i'm seeing. The runners are just a big shorter than a regular TPI system. it should breath well to 5500, but with that airflow you can make alot of hp by that rpm with the right cam. And since it flows so much, it will proby make good power to near 6000 or atleast hold that power that high

Thanks Orr89,what kind off numbers are we talking about for the cam?Maybe something like the Comp Cams XFI268HR?

that wouldnt be bad or use the XFI 268 grind like 1989GTA is using..also a very good cam but needs good valvetrain components, beehives or lots of spring pressure.
but i'd even step up to the 276hr or the cc503 grind which is the 276hr on a 112lsa.
both these cams have been proven off the shelf grinds. they will peak near 5800rpms which isnt bad at all for the FIRST i'd say. Might be the cam i'll be running but not sure yet

Another good cam is the LE1 cam from eportworks..its something like 225/232 i believe but has alot of lift. its very similar to the 503 grind but the lobe profile on the LE1 makes more power all over the curve and more peak.

I had ported the stock base out as far as it would go as well as SLP runners without cutting them apart and shortened their dividers to about the 1/2 point of the runner. The car would ET low 13.0s and high 12.9s around 105mph shifting at 5500/5300 rpm - shifting at 5700/5500 slowed it down around .05 seconds. I had severe traction problems and a low 1.9 sixty foot on average.

I did a minor clean up on the heads while they were off and swapped to a box stock FIRST unit and the ETs dropped to high 12.5s around 108 mph shifting at 5800/5600 - shifting as high as 6000/5800 slowed it down a couple hundreths. Shifting at 5600 from first to second would lay down 2-3 feet of rubber with the slicks and slow ets - so the FIRST was making a lot more power at shift recovery than the old TPI/SLP combo. Traction was a little easier to get and it would do 1.7 sixty foot times.

I know the minor work on the heads was worth no more than .15 seconds and 100rpm (from past experiences),, so I can easily say the box stock FIRST intake was worth a good .25 seconds and a couple hundred peak rpm over a fully ported shortened runner length TPI/SLP combo. The main benefit was it did roll off a little torque at the 3000 stall speed, but put MUCH more at the shift recovery. The engine had no problems running up a high as 6000 and by seat of the pants,, I felt like that was going to be the shift point. The track times said other-wise though. However,,,, that was becuase of the power at the shift recovery point was insane shifting at 5800 and under,,, and had less to do with the engine not wanting to pull past 6000. So,,, Orr is right about the engine being able to fill the cylinders better with the FIRST and making more power throughout the RPM band,,, basically a solid rise on the curve as opposed to just a few horses at the top of the powerband.

Cam wise, you want to run as much lift as you feel comfortable with. Same with duration. The fast ramp cams are perfect to get maximum filling while still being able to maintain a decent idle. So,,, if you think you can tune it,,, run it. Split on the exhaust duration will depend on the head's flow ratio and the car's exhaust system. Typically it'll need a little tighter than a single plane intake or MiniRam type cam.

Well we spent a good deal of time on the dyno this afternoon to try and figure out why the car will not make anymore than 350rwhp at 5000rpm. Couple of things. The new spark plugs took care of most of the electrical problems.

However I was still getting some squigly lines on the dyno readout. We changed out the distributor and that took car of that problem. Most likely the pickup coil. I will buy a new pick up coil and reinstall my old distributor.

As stated we did a lot of tuning and trying out different ideas. We ran the fuel tables between rich and lean. Ran up the spark tables and pulled them back. The best numbers on the dyno were about 355rwhp and 377 on the torque. We were as low as 325rwhp and 350rwtq during some of the extreme tuning. Again the power holds to at least 6000rpm as that is as high as we went on the dyno.

So horsepower did not change much but the torque did come up some. Probably because of the better air filling of the cylinders. However the mystery still remains to why the power is capped at 5000rpm and then holds there all the way out. Doesn't appear to be valve float but I will still hold out the posibility. Still mulling things over.

very interesting. i wouldnt think valve float at 5000 rpms, more like 5800 +

but those XFI lobes are very steep and aggressive over thenose so they will require great springs and lightweight stuff up top.

whats your springs like?

maybe its just how the intake is designed, it just cant get anymore out of it.

350whp at 5000 rpms seems like it should be peaking near 6000 and pushing 370whp +

That's what we thought. The valve springs are the Comp Cams beehive 26918 and are recommended by Comp for the XFI cam. The intake manifold before I did any porting on it flowed 301cfm on number one port which is one of the 2 worst. #8 being the other. So I'm sure it would flow at least 310 cfm right now.

The smallest point of the intake system is where the intake manifold meets the head. The cross sectional area is 2.2 square inches at that point. If need be there is plenty of material to open that part up some more.

I would think the high point of the horsepower would be somewhere around the 5700-5800rpm mark with that cam. Got some gremlins solved. Just got to think about the next move.

Thanks for the info Bad SS-89GTA Trans Am and Orr89rocz, this will help me in my decision on the first intake purchase.
Steve

Allen,, you didn't by chance unbolt the exhaust before the cats did you? If you didn't,,, and you swap converters and not much happens for your top end,,, you might want to try that. Obviously something is off and I don't think it's an air-in problem,, but it might be an air-out problem that's putting a cap on it.

BadSS you could be right. No we did not unhook the exhaust as there is no room under the dyno.

My MSD6A ignition took a dump going down the freeway last Spring. It started backfiring etc and I looked out the rear view mirror and saw red hot parts exiting the exhaust system. I figured I just blew out the cats. They are the new Magnaflow metalic substrate type that flow 580cfm each. So maybe one or both have collapsed in such a manner to cause some restriction.

When Dyno Don gets some time we can take a look at that part of the exhaust system. It was interesting that when we changed the distributor out it completely changed the air fuel ratio up to say 4800 rpm. It went completely lean. We are talking like 16:1 from say 13:1.

Yep the exhaust will be the next point of attack. Thanks, Allen

I have to chime in here and say, I did analyze the results on Datamaster and from what I saw, the MAP is showing signs of intake reversion.
It is bouncing all over the place. Starts at 101 and drops to 96-97-99-97- etc. Looking at the scan you see a wavy line all the way across. The exhaust does not exhibit any sign of restriction, it's just as loud as always (exhaust being my profession). The first indication of blockage is a change in sound, ie. wheezing.

Just my .02

Just an update as to where the project is at. As DynoDon suggested it looked like the valve spring were showing signs of weakness because of the fluctuation in the MAP.

Well I'm in process of changing out the valve springs and also the camshaft. A number of people thought I might be close to maxing out the camshaft so that is why I'm also replacing it. The valve springs have now been replaced. I have replaced the CompCams 918's with a Manley Beehive valvespring that registers 150# on the seat.

I took the old 918's over to Don's today to check the pressures. They measured between 95 and 100 pounds on the seat. This was at the 1.800" dimension. The installed height is around 1.760". We measured them at that height. There was virtually no change on the gage.

This is lower than I expected. When we installed them they were somewhere around 115#. So they dropped quite abit after they had been run awhile. I feel the seat pressure was no where near what it should be to run an aggressive cam like the Comp Cams XFI series. By the way they are rated at 130# on the seat at the 1.800" dimension. If they had indeed been that I would most likely not be making this post.

I understand Comp Cams has upgraded their 918 beehive valve springs and I can see why. So maybe one problem has been solved. We are trying to shoot for a dyno pull on 2/16/08. Not sure if the car will be ready by then. I'm having a heat dispersant coating put on the plenum, runners, intake manifold and cold air intake pipes. If I make the next dyno session it will depend on when I get these parts back.

One more thing. The Manley beehive springs were as advertised. They were right on the money.

I guess Kevin can keep his job then

good choice.. i'd recommend at least 150lbs on the seat with XFI rollers that want to rev to and over 5500. my custom grind will run 160-162lbs on the seat but its not a beehive

What cam are you gonna try now? i'm not so sure that xfi268 is done yet if it had valve float. i think you have 370 whp in that cam.

Thanks Ken!

By the way, the Manley springs are 221428-16 beehives for the LS1 engines. Manley doesnt make a steel retainer for these springs and 11/32" valves, but Allen says the Comp steel retainer for the 918 springs works. I'm going to mention this to my boss and try to get Manley to make a steel retainer for these springs.

It be nice to have the new AFR eliminator heads with the LS1 style lightweight valves in them those springs would be perfect for those heads and a very aggressive hydraulic roller

You are probably right in that the XFI268 cam probably has more in it. In fact DynoDon wanted me to just change out the springs and see what would happen as he thought that was the big problem. However my thing was once we tear into the motor again I might as well do it all.

I'm going with a custom cam with inverse radius lobes. It is a single pattern cam as my heads flow quite well and I have a very good exhaust system. The specs are as follows. 276/276 at .006", 228/228 at .050", 150/150 at .200" and the lift is .576" on both lobes with the 1.6 rockers I have.

Supposedly this will put my peak power around the 5800rpm range with a shift point around the 6200-6300rpm range. We shall see.

If for some reason I'm still not able to make anymore more power above the 5000rpm mark I will be totally perplexed.

what lsa is that cam on? i'd like a 2-4 degree split on intake/exhaust duration regaurdless of headflow and exhaust, but either way that sounds like a hot roller cam. Cant wait to see how that new First TPI reacts with those springs/cam upgrade. you should make more power past 5000 thats for sure.

It's on a 113 LSA. Got to pass California smog.

good deal, it should run good. longer runners dont really like overlap anyway

Cant wait to see the new results. Why is it that most of the fast TPI guys i know of here on this site are the california guys that pass smog?? lol i thought smog was suppose to hinder performance

Regarding the smog issue the biggest hindrence in the past was the catalytic converters. Nowadays with the high flow catalytic converters and running dual ones at that the problem at least at our power levels is pretty much deminished. The air tubes, egr and the rest really does not hurt power all that much.

By the way my total effective runner length with my moded TPI including the heads is around 14.5 inches. That is almost exactly the same as on the LS1 motors.

Thats about the same as an HSR i believe..maybe abit longer. Thats a good runner length. you should have the ability to really rev that motor up. you may have the most powerful TPI based intake motor i've seen yet naturally aspirated that is. I only know of a corvette that has a TPI setup that has run 10's n/a. i just dont know what else was done, but it must have been lightweight cuz i cant imagine it making much more than 400whp.

I think I remember that Corvette. He used to post on this forum but I can't remember his name. Anyways I think he was running a 383 or 408ci small block. I saw him post on another forum not to long ago and he has moved on from the TPI.

Edit: Maybe his handle was ski_dwn_it?

i remember that name but i'm not sure it was him who was running those times. If i recall it was a stock TPI as well which makes it more amazing

That's what I've been trying to tell the "old school" guys on these boards that want to rip off their "power robbing smog crap." The only thing that hurts you is the stock cat. Once you put on an aftermarket cat (they're all high flow now), the smog pump and air lines are only visually bad, they barely affect power (1-2 horsepower). I just crack up at guys with 15 second stock cars who remove their "smog crap" thinking their car will suddenly be a 13 second rocket.

We're also lucky in California to have a great machinist, JerryWho, who used to be a sprint car racer and had to think up all kinds of crazy ways to beat the competition. Now he applies those ideas to his TPI car and passes the info down to us.

Necessity is the mother of invention.

We're limited to the "legal" choices of aftermarket parts around here. Also, we can only upgrade to a newer motor, and it has to include *all* the smog equipment that comes with said motor, and pass a visual and sniffer test (it can't even show a check engine light.) Every year.

It makes the competition really interesting.

i guess that is a reason for your advancements in the TPI areas...

Definately a fine job. If more ppl paid attention to details, i'm sure more of them would have faster TPI setups.

i'm gonna build one someday when i get a new toy to play with. right now its hsr and 383

This is to finish up the thread outside of the final dyno pull. With the First Intake Manifold the plenum sits up about 1/2" higher than in the stock location. This caused some interference between my Hotchkiss strut tower brace and the hood. I thought this might happen so I had plan "B" ready to go just incase.

Plan "B" was to cut about 5/8 inch out of the strut tower brace to just beyond either side of the plenum location. I milled the 5/8" off and had a 1/8" aluminum plate welded in to form a gusset. The results are in the picture. Kind of hard to see with all the black but the outcome worked out just great.

By the way that black coating on anything to do with the induction system is a black heat dispersant thermal coating. Just trying to cool the air as much as I can. The jury is still out as to whether it works or not.

Link to the latest dyno results and my ongoing saga.

http://www.thirdgen.org/techboard/tp...ml#post3687783 (Dyno Results First Intake SLP Runners)