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Yes, I would see if another member nearby can help you and let you use their rig for logging to know for sure where you sit on the BLM's. You have some time, bucks, sweat, and tears into your engine build so you might as well take the last step and take it all the way.
If you send the datalog to Scott Hansen, I'm sure he can help fix it and send you a custom chip what will work this time.
If you plan on doing more work, I highly suggest investing in the Moates unit.
Here is what you do put nevada plates on it and do what ever you want to it.
This would require proof of residency in Nevada, to then register the car in that state. Hardly practical for the average job. Besides, several neighboring states have counties that do not require emissions testing for that matter. Not sure about California specifically.
Yes, I would see if another member nearby can help you and let you use their rig for logging to know for sure where you sit on the BLM's. You have some time, bucks, sweat, and tears into your engine build so you might as well take the last step and take it all the way.
If you send the datalog to Scott Hansen, I'm sure he can help fix it and send you a custom chip what will work this time.
If you plan on doing more work, I highly suggest investing in the Moates unit.
Sorry for the hijack to the OP...
I understand your concern with making sure the tune is spot on, but the process doesn't have to be so complicated (you're getting into tuning lingo).
C4 in Mesa really just needs a "wide-band" sensor (commonly used on dyno's) to get an AFR read. Some shops place the wide-band o2 sensor as close to the header-collector has possible, and some run it off the tail pipe (marginal difference in the readings). The operator, and what they're familiar with will dictate the accuracy of the final tune (if one is needed). Dyno shops will usually conduct a few pulls with the wide-band attached for a nominal fee. So to avoid the expense of purchasing a wide-band sensor, strap the car to a dyno (local shops charge $60-$100) and get a rear out of your RWHP AND AFR and lay the guessing game to rest.
I also want to clarify that C4in Mesa's corvette will fail a CA emissions test, since he's running long-tube headers (automatic fail in visual inspection).
The "old school" method of checking and adjusting for AFR was to read your spark plugs. Well seasoned veterans can get the AFR pretty close to ideal with this method (adjusting fuel pressure accordingly).
I've been in C4in Mesa's corvette and it runs fine. The cam he's running is suppose to be a grind that is functional with the stock computer. The MAF cars ARE more lenient to minor modifications as well. At the end of the day, he has a mild cam, with bolt-on's, so the AFR shouldn't be off wildly.
I trust the opinion and advise of these two men (both very well versed on this engine platform);
vader86
Tom400CFI
My advise, pay attention to the transmission and rear-end gear for an improved "seat of the pants" feel that will comply with CA emissions.
mnstrlt1: And Vader's suggestion was to get a tune with the cam in this thread.
Yes, Vader's stating it as an option. But it's not critical for C4in Mesa's cam selection and upgrades (or other mildly modified vette's). To get the "optimal" results, a true dyno tune would be the best option, followed by a mail order tune (which like you've mentioned, requires data logging to really dial it in and hardware that would cost just as much as a dyno tune anyway). By no means is a mail order tune (without data logging) optimal, it's an educated guess by the tuner.
Set the timing, check your AFR, and plugs, and adjust FPR accordingly. This is just another option (likely the most cost effective).
I did mention that I trust the opinion and advise of Vader86 and Tom400cfi because they have a ton of first-hand experience with what hardware combination can get you your end result.
I admit I'm not familiar with the MAF cars since I have a 1990. So you're saying it's not critical for Mesa to address this after the list of mods below? Is the MAF computer that much better than my speed density that it can absorb this amount of change and not have a problem? His list is about every bolt on there is. I just want to make sure since my brother has a 1989 and I want to give him the best advise possible when he mods his car.
Quoting Mesa:
Ported the heads exhaust some and gasket matched and ported the intake.
Comp Cam 08-501-8 new springs, rods and steel guide plates were required (Summit Racing)
This cam gets zero kudo's on this Forum and I don't understand why ? I didn't have to do anything but turn the key when the motor was finally all plugged in.
Roller rocker arms 1.5
Adustable fuel pressure regulator (turned the key and set the fuel pressure at 45)
Hypertech coil, 8mm wires
Balanced motor
Gasket matched and ported stock plenum, SLP runners ported, Edelbrock 3860
Open lid air intake K&N filter
Hedman long tube headers, Magnaflow cats, Flowmaster 44 mufflers, true dual 2.5" exhaust
Vader86 I totally respect your knowledge regarding the L98. However you say any cam change will require a tune to pass emissions. That is false. I have the Comp Cam 08-501-8 which gives me a 25-30 horsepower gain. I might add it gives me that gain along with the other upgrades. I strongly feel that they all work together and that is why I can run a 13 sec quarter mile and go from 0-60 in 4 seconds. In fact I have the stock ECM chip and when I tried a mail order custom chip it couldn't even allow me to put the car in gear. I just put the stock chip back in and my car runs great. I pass emissions and am at the top of the chart for acceptable pass or fail. I checked on line to see if it passes California standards and it squeaks by.
No, not every cam change absolutely requires the tune to be changed. E.g., simply switching to a ZZ4 cam which is almost identical to the L98's cam would not need anything done to the chip, you could do very well with just an AFPR and a little tweaking and it would pass a sniffer in Cali.
In general however, especially since he's in California and must pass emissions, I am correct to advise that the tune should be changed. I believe it should always be done to optimize everything once the cam is installed, and I know for a fact that a good mild cam will pass emissions if the chip is changed out there. If you have noticed, I tell everyone to do a custom chip after a cam change. If he wants to risk not passing, he can try that, but I wouldn't guarantee him that he'll pass. You may guarantee him if you like, and if he duplicates your mods exactly, he likely would.
So you're saying it's not critical for Mesa to address this after the list of mods below?
I have a few comments here. First, define "critical". It has become common place, I feel to recommend or even advise that a tune is "required" after any changes and that is not true, using my definition of "critical". As Vader said above, a tune is not always necessary. IMO whether a tune is "critical" or not depends on two things;
1. The combination of hard parts (cam, heads etc), and with regard to these hard parts, what REALLY creates a "need" for a tune is how the hard parts change the SHAPE of the torque curve, from stock. Fuel requirements need to follow the torque curve, and if we change (for example) from a mild cam, LTR combo to a long duration cam and a mini ram, we have dramatically changed the SHAPE of our torque curve and thus the fuel curve/map in the tune will be way off. It would run, but not well...which brings us to the second thing...
2. CRITERIA. What is "good enough"? I once put together a 400 to replace the 305 in a '83 Trans Am. I ported the intake, bored the TB's, used a 224/234 cam, headers, exhaust, etc. I was a ble to get it to run well on the stock ECM and chip (tune) by selecting the right injectors, fuel pressure, and base timing. What is "run well"? Here is where we define our CRITERIA, and that is a personal thing. My car idled like bone stock, it got 24 mpg on the highway, drivability was stellar (throttle response, smoothness, etc), and it ran low 13's. FOR ME, it met all the criteria I had, and it did not "need" a tune, IMO.
The criteria for the OP has an additional component that I didn't have to be concerned with in UT; emissions. So for him, if it drives well gets good mileage, etc, and is also able to pass an emissions test, then IMO he doesn't "need" a tune. Will it pass in CA? IDK. I feel that it could be made to, w/o a tune based on the parts listed by C4Mesa, but I wouldn't "guarantee" it either. Vader is recommending a tune b/c he doesn't want to send the OP to a test and risk a failure.
Does C4in Mesa "need" a tune? Probably not. He seems to be meeting all of the criteria that HE needs to meet. Did I "need" a tune on my 400? I'm sure many would argue that something was left on the table and I'd agree that something, although not very much, probably was. But w/o spending any money on tuning gear, software etc., I was able to get a set of performance metrics that I think most people would be pretty happy with. I was happy with it, so it didn't "need" a tune.
Originally Posted by vl5150
Is the MAF computer that much better than my speed density that it can absorb this amount of change and not have a problem? His list is about every bolt on there is.
The MAF ECM isn't a better ECM (b/c it's MAF), but b/c it's MAF, the thing is able to measure airflow into the motor, and therefor, better provide the proper match of fuel to the air. S/D ECM's calculate the air flow based on manifold pressure, engine speed, and VE tables in the tune. When you radically change Cam/heads/intake, you've radically changed the VE of the engine. If you make a "universal change", like I did w/my 400 (used more air everywhere, but same torque curve SHAPE), then you can add more fuel universally w/injector or pressure and get away with it. C4in mesa hasn't radically changed his combo, IMO. It's not the "number of parts bolted on" that require a tune or not, it's the effect that the parts have. C4in mesa's parts aren't radical. He's improved air flow some, pretty universally, and with a mild cam and LTR intake, probably not changed the SHAPE of his torque curve much. So "mechanical tuning" in conjunction w/his MAF seems to be "good enough", and it meets his criteria. Is there something left on the table? I'm sure that there is, but probably not enough to go through the expense and effort to make tunes to find it.
Drive a stock 1988 C4 and you will think different.
I have ridden in C4 in Mesa's car and my 88 vert. is completely stock. I can tell you, there is a tremendous difference in the take off from a stop light over mine. He has a lot of miles on his car also, doubling mine, but you wouldn't know it by the way it drives. First and second gear will set you back in the seat! I can only say this as this is my personal experience and opinion.
Tommy
i have an completely stock 88 vette with auto trans and 150k miles. The engine is tired and i would like to do some smog legal upgrades as i live in calif and use this vehicle to attend car shows and rallies. It has to pass emissions testing every 2 years. The stock hp for these engines is approx. 250. Is there a cam, intake runners and exhaust package or a combination of these parts that will increase hp to approx. 300 and still pass these strict ca emissions tests. Thanks for input.
150 is not a lot of miles if the maintance has been performed and it does not use oil. May be other causes for it not runing strong
I thought my SOTP was good until I measured and that's my point. Measure then act if necessary. Without data, there's nothing to base a conclusion on. I'm a IT systems engineer by trade and would not be employed for long if I couldn't back up my statements with data.
Here's the datalog composite of my 1990 after headers, Y pipe, and 1.6 RR's and a 43 PSI fuel pressure running the STOCK BIN. The green cells showed A/F ratio into the 16's and 17's on my wideband when on the gas. Car ran like a beast, but numbers told the rest of the story. I decided to tune after seeing this. YMMV of course. 1990's are more sensitive because of the speed density.
Doing my intake and runners now I've noticed that I'm hitting VE tables that the stock intake never was able to hit before. Some of these VE values are not really configured on the stock bin since the stock intake wasn't ever going to hit them. So at cruise the car will feel great since the computer is correcting for it, but it's really not optimized.
08-17-2014, 02:33 PM
