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I have the stock L03 in this corner, with a stock 91 L98 cam in the other corner. I wonder how bad it will run on the stock ECM?
T5, L98 manifolds, open exhaust. Would be installed to run final couple of races to get a benchmark for next year. Off idle performance doesn't really matter. Mostly half to full throttle all the car will see.
Not interested at this point in dropping the money for a tune or the time involved to do it myself. May have to swap from TBI to carb this winter anyways, so really don't want to waste the money. Again, just a baseline to see how it performs for next season. If I stay TBI, I'll get a chip in the spring.
So, how bad will it be? I know not full potential, but if its better then the stock L03 cam, I'll take it.
Again, not scientific, but I have three LB9s, two with an L98 cam and one with an L69 cam, (similar), and all three will happily rev past 6K RPM if I let them.
Well this weekend Im going to look around and see what parts I already have vs what I'll need.
It looks like if all goes well I'll have 2 races in July, then 2 weeks off before finishing the season with atleast 3, maybe 5 more races. Those 2 weeks off would be a real good time to start the swap. Even give me a weekend to fix any unplanned problems.
The only downside to all the work to swap the cam would be that I will probably have to go from a T5 to either a 700r4 or TH350 next season. If that is the case, I'll probably source a good roller 350 to use to help make up the power lost through the automatic.
But I would really like to see what the cam will do to the car now. If all goes well it shouldn't be that big of a swap, and I probably have almost all of the gaskets already. I will keep you all updated.
This past weekend some rumors came up about the future of the class, so right now Im on a standstill for any changes to the car. With only 3 races left, I don't see myself making any changes that I don't have to make.
If I do end up trying this, I will post back up, but at this point it would be atleast next spring time frame.
Well I picked up an ECM with a tbichips.com stage 2 already in it for a good price. If I do swap cams, I'll probably swap the ECMs to be on the safe side.
So, if somebody else wants to chime in down the road with results of an LO3, with a TPI cam on a stock tune, then feel free. I'll be running a modified chip.
But there is a slight chance I may do it, just to do it. Would be interesting during a practice day to see the difference an ECM swap would make.....
Well I think it will run, but like stated it won't be optimal. I'd get a VAFPR and bump up the fuel to about 18psi and throttle up the timing to about 10 degrees advanced. Of too much then bring it down to 8. What year L98 cam is it?
Exhaust will be stock TPI manifolds with a couple feet of pipe.
This is for a stock circle track class. So just playing around with stuff I have to see what I can get out of it. That's why stock intake manifold, and stock exhaust manifold. Cam will be at the limit of legality.
Ah, could you get away with vortec truck manifolds? With a little porting I think they'd be alot better than the L98 logs. Maybe find some stock L98/LT1 2.75 exhaust for the catback?
Not allowed to port. And I already have the tpi logs. Got to be alittle better then the l03 ones.
I would like to find one, if I can at a good price. If not I'll just piece something together. Going more for the "cheap and fun" then the "in it to win it". This past season was stock l03 with l03 manifolds and about a 12" piece of the stock pipe still attached to each side.
Running just a few feet of exhaust pipe may interfere with the o2 signal. I would be real Leary running a unknow tune. I have seen some of Brian's Harris work not that great.
i've seen tbichips tunes with minimum and maximum blm really tight so the trims never wander too far from 128, just so his VE tables look like they're working. that's pretty shady.
If you remove the rotators you will need to shim the exhaust spring to get the install height correct or depending on the head/spring may need to cut the seat. Comp 981-16 work well on stock heads or z28 springs.
Thanks for the input. I will definitely be building a better exhaust when I swap to the TPI manifolds.
The ECM had been ran with an L03 with an LT1 cam. I would assume it would be okay with the L98 cam??? I'm pretty ignorant when it comes to FI.
I may just run the same L03 springs, what do you think on that?
I'd get a wb gauge to see how it's running or use tunerpro rt.
I can't recall the lt1 cam specs there are a couple cams used. Stock springs good to .470
Id like to put something in just to monitor, but I don't want/need all the bells and whistles.
Are these decent or junk? http://www.ebay.com/itm/301799354964?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Or should I just take the plunge and learn tunerpro rt?
... about a 12" piece of the stock pipe still attached to each side.
Originally Posted by 3rdgenmaro
I will definitely be building a better exhaust when I swap to the TPI manifolds.
Take into consideration the length of pipe you'll decide to run. Although the effect won't be as pronounced as it would be with headers, there's still torque to be lost if the length is such that the reflected exhaust pressure pulse arrive at the exhaust port at the wrong time. Working with the length of "collector/collector extensions" has long been a tuning aid. One which may significantly boost torque compared to what you have now and perhaps even more than a cam swap might provide if your 12" of manifold extension is well off the mark.
Thanks Tuned. I'll look into it. I have a couple wideband gauges Im watching on ebay. Some are AEM and Innovative. I need to spend some time researching the tunerpro though.
Skinny, Im trying to figure out the best way, but at this point I haven't dug very deep into it. I'll be doing the work myself, so it wont be too extravagant. I have thought about trying to make a Y and running the exhaust out the passenger side, or just come down from the manifolds into a 90 and out to each side.
Assuming I run roughly the same speed as last season, or slightly faster, with the different transmission gearing, I'll normally be anywhere from 3500-5500 rpm. Just need to take the time and do some more research on it as well. Tubing diameter, dual vs Y, length, etc..
It's the length that proves to be important so the routing is constrained. That said, a couple of simple extensions either side has shown to be the easiest route and also more easily adaptable to modifications. The y-pipe limits your options going forward.
With headers and mildly modified engines, extensions of around 18" have been effective. Manifolds represent a different scenario although the fundamentals are more or less the same.
A few back to back test once the new tune is sorted out, using different "collector" extensions of, say, 18", 24" and 30" might yield surprisingly different results.
Just a couple of ideas as you move along.
Question: What does your intake consist of? I haven't read back to see if you have a carb, TBI or...
There are significant gains to be had with thermal management of an OEM configured intake manifold with carb or throttle body. All of them within the rules as I understand them.
Last edited by skinny z; 01-31-2017 at 09:39 PM.
Reason: added the word "intake".
Stock l03 TBI intake. Stock TBI unit but with a flat base air cleaner, no tbi spacer ring, and a tbi pod spacer.
I've read where a Y can help gain power, but like you said, routing is a pain. Plus you are going to have one side longer then the other. Right now Im leaning towards getting my first foot of pipe coming down from the manifolds, then to a mandrel bent 90. From there I haven't decided and really wont know until Im under the car and looking. Pointing them towards their respective door panels would give plenty of room to test with different lengths.
Probably go 2 1/4" since the manifolds openings are 2 1/4". Maybe 2 1/2" but don't want to go overboard. I have a flowmaster Y pipe I picked up cheap, but like I said, I haven't decided to use it or not. Its 2 1/2" in 3" out. Which is probably overkill for the little 305.
Last edited by 3rdgenmaro; 02-01-2017 at 05:32 AM.
If it were me (and it has been) I'd stick with individual pipes. That allows for some tuning.You'll be surprised at the difference a foot of collector can make. One way or the other.
Insulating the bottom side of the intake with foam and a heat shield is an easy and inexpensive to isolate the base of the manifold from the hot engine oil. There is a good tech article floating around somewhere that goes through the steps. If that's of any interest, I can see if I can't look it up. (It may be that it's part of one of my engine building texts. I can't recall). It is definitely worth some HP.
Hmmm. That is interesting. Something I should have looked at last week prior to putting the intake back on! Still something I will look into for the future though. Right now I've got to get the car track ready for practice at the end of the month. I probably will go with duals for the same reason you mentioned. It would be real easy to swap lengths during practice and see what changes it made.
I'd be interested in your test results too. It's a little tougher to quantify at the drag strip because the time for a test is so short. Keeping an engine in a spec RPM range for minutes at a time would allow for plenty of data collection.
As for the intake, I suppose you could build one on the work bench and have it ready as spare....
By the way, I run an AEM wide band gauge full time in the Camaro. That along with a vacuum gauge mounted next to it allows for some easily accessible information for carb tuning (for MPG as much as HP in my case). Data that will show the effects of tuning the exhaust too.
One big downside though is consistency. A lot easier to be consistent when you are only going 1/8 or a 1/4 mile straight. 4/10 mile on dirt is a little harder to be consistent lap after lap. Atleast for me at this point. Also moisture plays a BIG difference. From one practice round to the next, the track can really change a lot.
Im leaning more towards getting a gauge. That way I could use it on multiple cars as well for tuning.
It would be nice to set up the gauges where I can see them and the track on my gopro.....
Last edited by 3rdgenmaro; 02-01-2017 at 11:46 AM.
Well I have a new appreciation for people that build custom headers. Cutting and welding bends isn't easy!
I have an exhaust on the car. It is what it is. Passenger side turned out pretty nice, driver's side is alittle lower then I had wanted due to the angle from the manifold.
Each side turned out to be about 25" long. I have room to add some length for testing.
Ran out of time this weekend, but next weekend I hope to check fuel pressure, check some wiring, and get the car fired and timing set. From there I'll have to drive it and see how it is running. Hopefully it is good enough for practice session on the 25th.
Each side turned out to be about 25" long. I have room to add some length for testing.
I've attached a screen shot of the data entry page of the Pipe Max program.
If you want to fill in the blanks, I'll crunch the numbers to see if there's any indication what the "ideal" length(s) might be.
The only flaw here is that Pipe Max doesn't have a category for exhaust manifolds. The closest selection is for short style headers.
Still, there might be something useful to be learned.
305 so 3.736" bore, 3.48" stroke. I read somewhere saying CR with an l03 was ~9.3:1. Not sure I believe that though, but its a start. Shouldn't be higher.
Stock l03 heads, I read they are 1.84/1.50" but again not certain.
RPM, at end of the straights, I'll be maxed at 5500. IF the motor will actually turn that. If not...........Well, I'll have a lot of changes to make.
Some of the data is a little sketchy. I guessed at the intake centreline angle. Adding 4 degrees of advance is a typical grind so I sent with 100 degrees.
There is no input for an exhaust manifold . Short headers were the best fit.
What you will see though, when looking at the results is that changing the "collector" length can really effect power output. Witness how going from a best case 22" collector to a 33" worst case collector is only a matter of 10" or so.
While the numbers themselves may not reflect exactly what you have, the differences in the values certainly have merit. Adding or subtracting a few inches of pipe to the ends of your manifolds could make a world of difference.
If it were me, I'd advance that cam as much as possible to help build as much low speed engine torque as possible. Getting your dynamic compression near the limits of detonation is what will produce an engine with the best output given the limitations of the spec.
Track was dry slick so I didn't get to run as hard as I had hoped, but it ran good. Felt stronger then last year and some of the lap times I took were close to my fastest last year, even while letting out more in the turns since it was slick.
So for now, Im happy. I have a few things I need to tweak, but the cam and exhaust atleast added enough hp to overcome the change from t5 to 700r4. Will find out more in a couple weeks when we have a night practice. Track will hold more moisture then.
It'll be interesting to watch your developments. I'll also be curious to see if you'll manage any exhaust tuning. It'll be a pain in the *** process I would think what with having to add varying lengths of collector extension but it may make enough difference to get you to the front.
I haven't been able to do much testing, just too much going on. Did make the first race last Friday night though, which was the first time I really was able to push the car.
Setup hasn't changed. Noticeable difference in the car. Pulls good at least to 5500. Finished 2nd running the high side with several veteran 350 cars in the pack. Im happy with the difference. I'll try to play with tube length and swapping tunes later on, but for right now I have other things I need to do first.
So it might not be perfect, but l98 cam (and exhaust manifolds), on an otherwise stock l03 is a noticeable difference.
You've shown that a 305 can compete with a 350 in this category of racing. It may be that you've nailed the exhaust lengths on the first go round and that the other's (350's) haven't. There may be more power too but that part of the testing is difficult in that it involves a lot of physical changes. Adding collector length, subtracting length....If you can incorporate the thermal intake manifold treatments that were discussed, you may find yourself in the front of the pack.
Don't forget ignition timing.
It's great to see your early success.
Keep it up.
07-11-2016, 08:45 AM
