What Size Injectors

[andy-stevenson]

I know there's 1000s of topics regarding injector sizing, but haven't been able to find the information I'm looking for. Plans are to build the motor, twin a 72vvt with s483 and hopefully put down some big numbers. Truck is my daily driver and will see the strip throughout the summer on weekends. I'm trying to decide between 60 and 100 overs, the only thing I'm unsure of is how larger injectors are going to perform in the -20* weather they'll see in the winter. I plan on keeping the compression higher to help with running in cold temps just wasn't sure how large I could go with having issues. 60% or 100% overs?

 

[LWATSON]

My truck is in the shop getting 60s right now. It was suggested to me to get 100s if I had plans to build the engine. With a stock engine /fuel system the suggestion was for 60s.sorry I can't help you with the cold weather issue.

 

[S Phinney]

100 overs in your case Andy. No question about it. They will be just fine with quality injectors and quality tuning.

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[andy-stevenson]

Ok. So with compression up around 16.5 or 17 and 100% overs you think I'd have no issues running the truck throughout the winter? Can 100% overs be run with a stock, single cp3 and small pulsewidth just pushing a 500horse tune?

 

[Harbin_22]

I have a billet 4094vvt/483 setup. With 60% and dual pumps, it took 2800pulse to make 900hp. On 100% it took 2650 to make 980 HP. I would do at least 100% if you want 1000hp. Cold starts shouldn't be an issue with correct tuning and probably leave the glow plugs in it.

 

[OregonDMAX]

How much does elevation play a role? Especially with colder temps

 

[Hot COCOAL]

Jon's oval bowls @ 16.5 CR
100 overs
12mm Exergy CP3 or dual stockers
And go with a S485 or bigger...

Weather will just require a longer warm up time, but if you use the block heater starts should be fine

As far as cold weather and altitude, I'd imagine it shouldn't be an issue as much as when the weather is warm, cold air is more dense, but that's just speculation

 

[S Phinney]

Ok. So with compression up around 16.5 or 17 and 100% overs you think I'd have no issues running the truck throughout the winter? Can 100% overs be run with a stock, single cp3 and small pulsewidth just pushing a 500horse tune?

At 17:1 ratio be careful or you will crack a piston. That much cylinder pressure and HP capability you would be better at 16:1 no more than 16.5:1.

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[Hot COCOAL]

At 17:1 ratio be careful or you will crack a piston. That much cylinder pressure and HP capability you would be better at 16:1 no more than 16.5:1.

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Yeah man, I wouldn't even consider 17.0/1 CR for anything
Stock is 16.8...
16.5 is pushing it for 1000hp goals but acceptable
Anything close to or definitely over 1000hp you should really consider 16.0/1

:2cents:

 

[hondarider552]

100's. I ran with stock Lbz cp3 @ 1500us for 6 months just fine

 

[hondarider552]

Jon's oval bowls @ 16.5 CR
100 overs
12mm Exergy CP3 or dual stockers
And go with a S485 or bigger...

Weather will just require a longer warm up time, but if you use the block heater starts should be fine

As far as cold weather and altitude, I'd imagine it shouldn't be an issue as much as when the weather is warm, cold air is more dense, but that's just speculation

Do you have any experience backing this statement?

 

[PACougar]

Do you have any experience backing this statement?

Why would you even ask:roflmao:

 

[Hot COCOAL]

Do you have any experience backing this statement?

Just 2yrs of reading this forum and putting up with shit from guys like you
3yrs of calling shops across the nation talking to builders, and
Driving and building my own truck for 3yrs now...yeah, I know that's not much

Why Brian? Was there an untruth in what I said?

My summers are about as cold as your winter...when's the last time you were in sub zero temperatures? Desert boy...

You also made somewhere around 1000whp on stock manifolds and cam etc etc and don't seem to care if/when shit breaks...not exactly what most are willing or trying to do

 

[dirtydmax]

Hey andy,our winters are -40 up here and I am wondering the same thing about driveability with bigger stix in colder temps.will tuning play a part in colder temps and lots of fuel for driveability?

 

[LWATSON]

Are there different values commanded depending on ambient temp? I believe so, if this is true it seems to me your tuner can alter cold temp values to help with cold operation issues. I know very little about the technical side of EFI so take my thoughts with a grain of salt.

 

[dirtydmax]

Thanks for the insight,I am looking for a turer but have NO idia what im looking for and why,I know there are many good tuners out there but have nothing to base a decision on so,Sorry for the hijack!

 

[S Phinney]

Are there different values commanded depending on ambient temp? I believe so, if this is true it seems to me your tuner can alter cold temp values to help with cold operation issues. I know very little about the technical side of EFI so take my thoughts with a grain of salt.

Most all temp related modifiers are limiters. Compression , injector quality and good tuning would be your answer. Dynamic compression is more important than a static compression ratio in this matter. Camshaft profile , quench come into play for that as well.

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[LWATSON]

Good thing is in my personal opinion the majority of the top notch tuners are members of this forum, someone correct me if I'm wrong but the sub par guys don't last long and leave here? Don't get me wrong there are other great tuners that don't come on here but you wont go wrong with the vendors on this site.

 

[LWATSON]

Most all temp related modifiers are limiters. Compression , injector quality and good tuning would be your answer. Dynamic compression is more important than a static compression ratio in this matter. Camshaft profile , quench come into play for that as well.

Sent from my XT1080 using Tapatalk

Gotcha, so really nothing that would be an aid in dialing in for cold startups.

 

[PureHybrid]

Lots of tables for cold starts IMO. Adjustments based on ect and iat are all over the place on the base file. Whether they need modified or not is the question, I'd imagine some serious frp would be needed to cleanly burn 100% overs in -30 temps. I feel that the only thing that is seriously limited during cold operation is high end fueling, boost (for us vvt guys), and high end timing. But wtf do I know