Went on first cruise to feel things out. Hammered it in 2nd, around 4000 rpm and got some detonation right away. Hammer it in high, around 3500, only a little detonation around 4500 til I let off (soon after).
Combo, 440 mopar,
9.3:1,
236/242 @ 50 110lsa,
s400 (75mm) 1.32 ex.,
open chamber alum. heads
24 deg. timing locked
9 psi
93 octane shell gas
solid 11.5 afr
ngk 7 recessed race plug
no intercooler
engine temp was 165-170
I'm thinking just plain not enough octane, but thought I could at least get away with it a 9 psi. Have an AIS meth kit, but not using it now/yet. should I try less timing? Seems pretty low already for BB mopar. Just want to rule out everything but octane before I try the injection.

 

I would back the timing down to 20* and see what happens. Being non intercooled I would be real conservative on the timing. Do you have any way to log iat temps? May also want to put some ngk 8's in there.

Anthony

 

I agree, i would even go further and back the timing down to 16* and start from there, the NGK 7's should be plenty cool enough.

 

I guess I'll start with timing and see what happens. Find out in a few hours.

 

OK
440 + 75mm + pump gas - intercooler + 9 psi = Knock

A engine that size is working the 75. The 75 is making some heat to try and fill the motor.
You need and intercooler or better gas.

 

chemical intercooler . I'm sure I'll need it, just thought I could get away with 9 psi without.

 

Decided to try using the meth first. Single 14 nozzle in charge pipe. Big difference, just barely a hint of detonation in high. afr now 11.7. using washer fluid. Went back and adjusted the main bleeds, was 020 rear/026 front, now blocked rear/018 front. pretty much no detonation, but weird thing is, afr stayed the same. Have a second 5gph nozzle I can add, or go with more meth. percentage.

 

Is there a reason you didn't go with an intercooler? There are sponsors here that can set you up with one for around 200. That meth kit probably cost that much if not more to do. I know some of the piping would have to be changed, but i think you are playing with fire relying on that meth all the time. It's gonna cost you head gaskets, or worst case new pistons/rods/bearings. You need to back that timing down, especially if it is still detonating with the meth. Is your fuel pressure rising at 1:1? Your best bet would be to install and msd digital 7 and set up a timing map that will benefit light load cruising as well as full throttle applications. Take it for what it's worth, but I would hate to see you damage a brand new combo.

Anthony

 

no room for a/a. don't want a/w, its a street car.

 

Classic mistake. You have started changing the fuel curve to fit the spray. Now if anything happens to the spray, nozzle blockage, pump failure, etc... your screwed because you tuning for it.
Don't have room. Plasma cutter is you friend. Hot rodding is about making it fit.

 

I would at least do one of those pipe intercoolers. It's like a 3 or 4 row tall and not more than 4 inches tall.

Ooor.. lower the timing a few degrees..

 

I dont believe it should be detonating.

9 psi ??? With the correct cam and ngk 9 plug you should be able to run that thing NON/IC at 25- 30 deg. timing. on pump gas with that amount of boost.
Im not saying go crank the timing up or that your cam is wrong. There is defininetly something not working with the combo that is causing it.
Turning the timing way down brings on more issues with increased exhaust temp and sluggishness.

Make sure you are getting inlet air from out side the engine bay. Under hood temps can amplify inlet temp badly.

 

To me, air to air is useless on the street, by the time there is enough airflow through it to do anything, the motor would have detonated already. Plus, I don't want an intercooler as my grill and bumper.
As far as the meth failing, ANYthing can fail, pump feeding the engine could fail, people run nitrous it can malfunction and burn stuff.
I reduced the timing from 24 to 18. Helped a lot, still drives good, responsive. Had a passenger to get a better look at the wideband, it's right at 12:1, so maybe a little lean still. Getting air from fenderwell, and the car is hoodless right now. I think the combustion chamber has a little something to do with it also.

 

Really, a S475 is making heat on 400 inch engine at much over 15 psi. A 440 with an S475 is not far from being over.

A/A on the street, they work for us but each there own. 8-10 psi without and 15 with.
Keep your wipe tank full.

 

I cant argue with the turbo making too much heat. Very well could be the problem.

Still comes down to somethings not working in the combo.

 

Too little information is given about the cam to say what is happening. For instance, one cam 218 @ .050 and 137 @ .200 has .365" lobe lift. #2 cam is 220 @ .050 and 147 @.200 has "only" .345 lobe lift. The second cam produces much more cranking compression. We need more details. Start with less timing, too. I wonder how much back pressure you have on the 440 with that turbo?

 

i went from 9psi to 13psi plus more agressive timing with an intercooler on the street. they work, but i agree they change the look of the car. I had to make my own grill and remove gt style fog lamps...but it was still worth it.


I wonder if the open combustuion chamber would have something to do with it? two flame fronts causing some detonation...i dont know. just an idea

 

FWIW. I'm running a 452" BB mopar in a 4050# car. I share your feelings on the intercooler issue so this is what works for me. 80mm turbo, EV hat, 800 edelbrock, performer intake, iron 452 heads, 8.9 to 1 compression, 241/247 .545"/.545" 114 sep. 107 icl cam, headman shorty headers. 94 octane, 28* timing, 13# boost, 11 to 1 a/f ratio. Ran 121.7 mph three times last weekend on traction limited whitewalls. No deto. Oh yeah. Spraying 250cc/min into the compressor and 500cc/min after. Both nozzels start at 3lbs.
If you try to compress 150 degree underhood air, the air going into the carb could be hitting 300 degrees.

 

An a/a WILL NOT fit plain and simple. Plenty of people on here run the injection with results as good as if not better than an a/a, so i'm okay with running it. So, now im cooling the charge. I can tell u exactly what the cam is, its a comp xs274s, if u want lobe specs i will look those up.

 

So when the timing was reduced to 18* you still have detonation?

Something is not right.