Maybe Dumb Question

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.
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proutyc
Posts: 104
Joined: Sun Sep 04, 2011 6:59 pm

Maybe Dumb Question

Post by proutyc »

On my race car I have it running on as batch fired.

My question is....

Does this mean in effect I'll consume twice as much fuel compared to sequential?

As we do 10 minutes races and if the above is correct I'd have an additional 10-15kg. at race start than what would be needed

Thanks in advance
Chris
stevieturbo
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Re: Maybe Dumb Question

Post by stevieturbo »

proutyc wrote:On my race car I have it running on as batch fired.

My question is....

Does this mean in effect I'll consume twice as much fuel compared to sequential?

As we do 10 minutes races and if the above is correct I'd have an additional 10-15kg. at race start than what would be needed

Thanks in advance
Chris
No.

Whilst full sequential may be more efficient in terms of fuel use. It will be a relatively small amount.

At lower loads your injectors will fire twice per cycle, but pulse widths will be almost half because of this.
proutyc
Posts: 104
Joined: Sun Sep 04, 2011 6:59 pm

Re: Maybe Dumb Question

Post by proutyc »

Many thanks for the response.

I have no ideas on this one, just know its alot more beating on the motor on the dyno. But I was thinking I'd prefer the driver to able to be the only one carrying excess weight (me) not the fuel tank if possible.

Are we saying like 5-10% and not 50% more fuel?

Thanks
Simon P.
Posts: 96
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ECU Model: S100 Pro
Firmware Version: 61
Location: Montreal, Canada

Re: Maybe Dumb Question

Post by Simon P. »

In a batch fire set-up the injector opens once per revolution for a given cylinder so some of the fuel just sits on the intake valve of that cylinder until it opens and gets sucked in. Does this mean the engine injects twice the needed amount? Well, no. The ECU knows how much fuel it needs for a complete cycle so although it opens twice to meter that amount the amount hasn't changed.
The advantage of sequential is that the injector only opens once and that it can be perfectly timed with the valve opening which is good for emissions and idle/low RPM use. The disadvantage is the increased complexity (need cam sensor) and one injector per cylinder is mandatory.
On a batch fire set-up one injector can be used on multiple cylinders through clever intake placement, like higher up in the plenum.
And once the engine RPM climbs above a certain point the difference between batch VS sequential is non existant as the cylinder filling events happen very fast.
stevieturbo
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Re: Maybe Dumb Question

Post by stevieturbo »

proutyc wrote:Many thanks for the response.

I have no ideas on this one, just know its alot more beating on the motor on the dyno. But I was thinking I'd prefer the driver to able to be the only one carrying excess weight (me) not the fuel tank if possible.

Are we saying like 5-10% and not 50% more fuel?

Thanks
Every setup will be different. It will depend on cam, overlap, heads, tuning etc etc

But there isnt a chance in hell it will be anywhere near 50%. I would doubt even as high as 10%

If fuel economy or weight really is that critical, then go fully sequential and tune on each cylinder on the dyno to make the most efficient use of the fuel you are injecting. Taking the time to do this may give you that 10% you seek.

But it's going to take a lot of time and money testing to achieve it.
Simon P.
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ECU Model: S100 Pro
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Location: Montreal, Canada

Re: Maybe Dumb Question

Post by Simon P. »

I've read it's actually more around 5% and only with RPMs below 3k. Above there's practically no difference. And for a race car which spends most of it's time well above 3k I wouldn't worry too much about low RPM economy or emissions! :D
proutyc
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Re: Maybe Dumb Question

Post by proutyc »

Awesome thanks guys. That'll save time and money abusing the engine on the dyno for sure. Batch it will stay.

thanks Stevie and Simon. much appreciated
stevieturbo
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Re: Maybe Dumb Question

Post by stevieturbo »

Simon P. wrote:I've read it's actually more around 5% and only with RPMs below 3k. Above there's practically no difference. And for a race car which spends most of it's time well above 3k I wouldn't worry too much about low RPM economy or emissions! :D
Many do say that sequential does offer better power, economy and response under all circumstances.

Gains would mostly decrease as IDC approaches 100%, but when duties are much lower, then there is potential for better performance and less wastage.

Every engine will be different though, as there are so many other variables.
proutyc
Posts: 104
Joined: Sun Sep 04, 2011 6:59 pm

Re: Maybe Dumb Question

Post by proutyc »

Thanks

As I said I was sure it was dumb question. I was thinking of the problem as if it was direct injection. May look at it further down the track but if its only a few percent its not a big deal

Thanks again for the education.
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