What's everyone's opinion on timing greater than 600hp @ 5800rpm at about 12psi with Advanced Induction 200cc, D1SC, about 8.9:1 compression on 93 octane thru full headers with magnaflow catback, 93 octane, 11-12:1AFR?? I have about 24 degrees using an MSD Pro-Billet (not sure if there's degree error).

I've been wanting to push it a good deal past 6000rpm but when I do (two times now) I get some knock not sure if it's false or real and havent tried race gas or taken the exhaust off yet.

This is also the first time I've been above 9psi, no knock at 24 degrees at 6000rpm, now Im getting some around 11-12psi and 6000rpm, everything else unchanged.

 

I forget your setup. What do you have for intercooling/aftercooling? and What spark plugs?, ignition amp? Fuel system?

 

24 is about where you want to be.

Richard

 

I have the stock Twins for intercooling, 3.4" pulley and the stock crank pulley. Plugs are the TGK TR6, with MSD Pro Billet and MSD-6AL, along with some MSD wires I dont remember exactly what ones.

Fuel system is stock except for 83lb/hr injectors and a Walbro 255 pump, as far as I can tell Im not leaning out but I do get a little upswing in the AFR at the end, but still about 12.0 to 12.5. 93 octane, the IAT temps were cooler when this was happened,80-90F, it doesn't do it all the time but seems the higher I rev it the more likely it is to happen. I was thinking maybe i was leaning out a cyl or two? I have the Wideband on the dside pipe (last fuel rail to get fuel).

 

I'm not sure why you would get knock that high in the rpm band. I wonder if your valves are floating or something. Did you rev to 6000+ before? More boost can work against your valve springs if they are marginal at high rpms. If you don't think it's that and you're sure that you're not leaning out, you could go one colder on the plugs and see if that helps. I don't see how that fuel system is adequate, but that's up to you to decide.

 

I've never really been able to take it above 6000rpm since it feels like most of the power is below that (it screams to about 6000rpm then I shift).
Your thinking valve float can cause knock? Power has always seemed to start falling off near 6000rpm and that's why I have never made it far above, it seems to pull harder just below 6000rpm then kinda hangs there as the tires re-grip... torque is falling in that rpm area so I dont know if that's what Im noticing or if it's actually starting to run out of steam.

Fuel system is on the edge, I know that and thinking now is a good time to add a pump and see what happens.

If floating valves is any how related to knock then possibly that is occuring, but my setup should turn 700-750hp as listed on the AI site.. the last guy spun to 6500 no problems, same springs, procharger, etc but they did say the cam was just slightly different hoping for more power?

 

I wasn't equating valve float with knock, but it will run crappy if you float them. Chances are, you have one of the other problems that I mentioned. But if you are running out of power because of cam or fuel, then why would it knock? Knock is usually associated with torque.

 

I cant see how a single walbro, even at 14v, would be enough pump for a d1sc setup @ 10+psi. I would put another one in there if I were you. If you still have knock retard enabled, that will cause powerloss. If it pulls 4* and yer at 24, thats quite noticeable. Cant see 12.5 afr causing detonation though with those IAT's.

 

ok, cool, thanks for the ideas I'll probably work on adding another pump and see what happens.

It doesnt always knock in the upper rpm, I would say only 1/2 of the time.

I could see this happening if fuel pressure is dropping a bit, the flow to the rear injectors would get the least fuel since they are at the end of the rail so maybe it's possible the rear dside cylinders are leaner than 12.5 average of the 4 on that side.