V-8: 2 squirts or 4 squirts?

re-animator · Post by **re-animator** » Sat Aug 19, 2006 9:04 am

Hi!

just went around the block on idle, more or less. I watched the "dot", and yes, indeed it's a 2 person job! Thankfully there's not much traffic here on saturday morning.

My question for today is: 2 squirts or 4?

V-8, rails in series. I'm more interested in performance than economy, but I've found good tuning is usually both, at least with a carb.

thanks!

krisr · Post by **krisr** » Sun Aug 20, 2006 1:39 am

I use 2squirts alternating on my 400. Rails in series also with 8x42lb/hr injectors setup. My req_fuel is 12.5 and have no tuning issues with high impedance injectors, the performance is brilliant aswell. Once I get AE finalised between gear changes hopefully i'll have some time slips to see if it was all worth it

re-animator · Post by **re-animator** » Sun Aug 20, 2006 7:32 am

Krisr,

I'm running reqFuel of 12.5, too. I've been using 2 squirts, but I just thought I'd ask if there's a better way.

There's just a few things I need to modify on my VE table and Accel Enrichments and then I;m going for a drive. We put about 23 km on it yesterday. It would have been more but there's a lot of idiots on the roads up here, and my driver got a little annoyed by traffic driving a car like mine so we shut it down.

I've got a stumble at throttle tip-in during accel, and a bit of tuning for highway driving. I'm only a "little bit" excited!

I'm going to run a search for a Holden Manaro HQ to see some pics. I've actually never seen one.

thanks!

krisr · Post by **krisr** » Sun Aug 20, 2006 9:22 am

The new X-Tau code (2.6x) really helps for tip-in lean spots. Manual transmissions and an engine with alot of torque doesn't really need alot of throttle opening if your plenum delivers alot of airspeed. I found that MAPdot based AE helped greatly for my application, but with the 2004R you may find that TPSdot will succeed. I also found that a TPSdot in the neighbourhood of about 4.0 seemed to trigger well with my LS1 throttle body.

Good luck!

Btw, here's a couple happy shots of the car/engine (before i converted to series plumbed rails)

re-animator · Post by **re-animator** » Sun Aug 20, 2006 3:05 pm

SWEET CAR! I think I need one. Could you put a couple of stamps on one and send it up here? We don't get a lot of Aussie stuff up here, even in the magazines. There is a guy with one of the cop cars from the movie "Mad Max". I forget what the model is, but he's got it painted just like one, with the cop lights and everything. I see some cars for sale on eBay, but that's about it.

I just set my TPS to 4 and it seems to run well. I'm looking forward to getting to work with MSTweak and getting it down right. If I have the O2 sensor on it runs a bit odd. I'll keep working on it.

thanks!

TPI 85 Blazer · Post by **TPI 85 Blazer** » Mon Aug 21, 2006 6:02 am

The way I understand it, less squirts is always better than more, unless something forces you to the higher number. Going from 2 to 4 squirts, cuts your idle pulse widths in half, so you lose precision on the idle control. You also lose one opening and closing time on every cycle, so you have like 2ms less total time to inject, so you actually have less fuel capability at 4 squirts.

Maybe somebody else can comment on where 4 (or more) squirts is a big advantage.

65looter · Post by **65looter** » Mon Aug 21, 2006 6:35 am

TPI 85 Blazer wrote:The way I understand it, less squirts is always better than more, unless something forces you to the higher number. Going from 2 to 4 squirts, cuts your idle pulse widths in half, so you lose precision on the idle control. You also lose one opening and closing time on every cycle, so you have like 2ms less total time to inject, so you actually have less fuel capability at 4 squirts.

Maybe somebody else can comment on where 4 (or more) squirts is a big advantage.

nice one, good info

cheers

krisr · Post by **krisr** » Mon Aug 21, 2006 2:55 pm

TPI 85 Blazer wrote:The way I understand it, less squirts is always better than more, unless something forces you to the higher number. Going from 2 to 4 squirts, cuts your idle pulse widths in half, so you lose precision on the idle control. You also lose one opening and closing time on every cycle, so you have like 2ms less total time to inject, so you actually have less fuel capability at 4 squirts.

Maybe somebody else can comment on where 4 (or more) squirts is a big advantage.

OEM cars came with 2 squirts in bank fire so it cant be all bad

... I also found if you can get away with raising your fuel pressure, then lowering your req_fuel constant it will promote atomisation. I read in a Kinsler document that they recommend running as much as SAFELY possible.

Kris