Alright, I have a 388 stroker that I just built, has about 6k on it. I want to get it dyno'd. Here are the issue's I am concerned about. If you guys need a mod list to determine what needs to be done let me know, I may even post it.

1. My cam is pretty big for this setup, .579/.584 and the heads are ported, robs vacuum so much that when I hit the brakes at 100+ mph the engine will shut off because there's only enough vacuum for the brakes.

2. Clutch is worn so when I heat my tires at the track it slips because the car hooks up and it can't handle the power so I'm at a loss there, at the track I just go around the water and dont heat up the tires.

3. My injectors are stock injectors tuned up to 26# and my fuel pump I believe is stock, but Speedworks charged me like 800$ for a new one so I dont think it is stock. My worry is if this is enogh fuel for the engine, I dont wanna run out of fuel on the dyno.

4. I have a couple codes, bad o2 and MAF sensor, should I fix these before tuning? Probably right because of A/F ratio which is used for tuning.

5. And last, I am getting valve/cylinder noise which I believe is because of running 93 octane, I think I should be at 100+ octane because of the 11.7:1 compression, should I tune at 93 or 100? I used 93 to drive daily.

Sorry it is so long and thank you for all of your input. If you need to know my mods etc. I think I have some in my sig.

 

I'm no expert but I think your injectors are too small, maybe some 36lb injectors, as for the fuel I have heard of people running 12 : 1 compression on LT1 engines with 93 octane, so it should be able to get tuned for 93 octane

 

Your fuel pump being stock or not has me confused...What did they do for $800? and I agree that 26lb injectors are probably going to be too small...6K miles and just built? What are your cam specs? Who did your heads? What cylinder noise are you hearing? detonation? Imho, you need to address the stalling issues, the codes, clutch, the noises you are hearing,etc before going to the dyno...

--Alan

 

you didnt give duration numbers on the cam or specs on your heads

1) Vacuum should never be an issue when you are driving at 100mph. It only becomes an issue at low rpms. A 388cu motor should do ok with a 240ish duration cam in terms of vacuum. There is likely another reason why your car shuts off. If vacuum is that big of an issue, you should get a vacuum cannister.

2) Re: your clutch, you'll need a new one, no tuning can fix that There are many options... if you can cough up over $1k then a mcleod street twin would be the best option

3) Stock injectors are 24#, am not sure why you have them tuned to 26s. As mentioned you will need bigger injectors. Just because they charged you $800 for a fuel pump does nto mean they put in an aftermarket one. A walbro with the wiring kit from racetronix should cost less then $300. I paid $800 CAD for a stock fuel pump from GM when I was young and stupid.

4) You'll definitely have to get the codes sorted out. You may need new o2 sensors... its not common for MAFs to fail. If your tuner is nice, he can tell you what those things are reading out to the pcm.

5) As mentioned, you should not have knock unless your timing is too aggressive or your cam is too small. 11.7:1 is not too much compression for a big cam and reverse cooled heads. if the noise goes away with 100 octane, then it is knock, otherwise its something else

good luck sorting these things out

 

Thanks for the input guys.

I dont know why when I am going 100+ MPH and hit the brakes hard the car does shut off, and I think I do need a vacuum canister. I am not sure why it shuts off but it does, wish I did and it didn't do it before my rebuild and with the cc306. The fuel pump I will prob replace, and injectors but someone said they ran out of fuel with 36# injectors. My 388 does run kinda crappy due to having a 360 ci tune on it with a diff cam and not having headers before. The heads are great flowing so they can handle the power. I will get rid of the codes and I am hearing a valvetrane noise from the cylinders, it's not knock, I know what a knock sounds like, more like a rubbing or such. Someone told me if I'm using too less of an octane the you will get valve noise and lifter noise. I am pretty sure that's what the noise is but not what's causing it, maybe my lifters are shot. Also the timing may be aggressive due to my last tune and it does run really really rich due to o2's etc and crappy tune so that may be causing the noise. Is there anything else I should consider? The cam specs are

Cam Style: Hydraulic roller tappet
Basic Operating RPM Range: 2,200-6,200 RPM
Intake Duration at 050 inch Lift: 242
Exhaust Duration at 050 inch Lift: 248
Duration at 050 inch Lift: 242 int./248 exh.
Advertised Intake Duration: 292
Advertised Exhaust Duration: 300
Advertised Duration: 292 int./300 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.584 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.579 in.
Valve Lift with Factory Rocker Arm Ratio: 0.584 int./0.579 exh. lift
Lobe Separation (degrees): 113
Computer Controlled Compatible: Yes
Grind Number: 292XFI HR 13

 

Anyone else please?

 

Okay, If I get opti I will get Accel, what is the best fuel pump for in tank or if I can use outer pump and make it work which one? Also what is the best injector? Thanks

 

it would be best to find out what fuel pump you actually have.

Racetronix makes very good injectors. Im sure there are many other good brands. If your dyno tuner will not charge you twice, it may be easier to just swap to bigger injectors while you are at the shop, have a tune put in right away to account for the injectors, then dyno tune the car. If the car is running leaning up top despite correcting the A:F and NOT maxing out your injectors, that would indicate that your fuel pump is not delivering enough fuel.

Any walbro 255l/hr pump will be more than sufficient, and they are affordable. Putting them in is plenty of work unless you do the "trapdoor method", i.e. cutting a hole in the body between the trunk and rear seats to access the fuel pump, then building a trapdoor to close it.

 

Well guys I would find out what fuel pump I have but the tuners who changed it went out of business and I have no kind of reciept showing what the part was, just the price and this was about 2 years ago. My 388 is running really rich and never looses gas right now so I dont know, it's not starving my engine at high rpm's but I havent had it tuned either huh? I will see about the fuel pumps and injectors and hopefully this all will help.