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Myblackhatch
Joined: 04 Oct 2011
Posts: 51
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 Posted: Sat Dec 17, 2011 10:19 am Post subject: Boost vs timing |
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So I went to the track last night with a few friends. We all go to support a friend with a local shop and his car.
Now the car is a civic coupe with a ls/vtec setup on boost. Built bottom end but no sleeves. using c16. I didn't personally tune the car but I was there when they did.
to be honest the car has a tone of potential left in the tune. The tuner started tuning the timing map and once it made a certain horsepower the owner of the car was happy and said just leave it how it is. A/f is good and very conservative timing values.
Now last night after going to a test and tune we ran a 10.14 in the 1/4 I think at 139mph. Now we all want to see the car in the 9's and the debate started right there.
I said i think if we added some timing in and left the same amount of boost, that would be the best way to achieve our goal. I am keep cylinder pressure in mind due to stock sleeves and knowing how the tune looks. The owner said he would rather have more boost and leave the timing alone.
So my question comes down to really what would be safer for the motor? more boost or more timing???
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keithmac
Joined: 14 Nov 2010
Posts: 64
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| Posted: Sat Dec 17, 2011 12:16 pm Post subject: |
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Depends on how efficient the intercooler is, where abouts in the compressor map you would be if raising boost etc.
I like timing over boost personally as it makes the car fell more responsive.
People see the Supas running massive boost and single digit timing numbers and all want to follow suit to be honest.. |
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Roberto Arano
Joined: 22 Nov 2005
Posts: 358
Location: colorado
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| Posted: Sat Dec 17, 2011 1:47 pm Post subject: Re: Boost vs timing |
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| Myblackhatch wrote: | So I went to the track last night with a few friends. We all go to support a friend with a local shop and his car.
Now the car is a civic coupe with a ls/vtec setup on boost. Built bottom end but no sleeves. using c16. I didn't personally tune the car but I was there when they did.
to be honest the car has a tone of potential left in the tune. The tuner started tuning the timing map and once it made a certain horsepower the owner of the car was happy and said just leave it how it is. A/f is good and very conservative timing values.
Now last night after going to a test and tune we ran a 10.14 in the 1/4 I think at 139mph. Now we all want to see the car in the 9's and the debate started right there.
I said i think if we added some timing in and left the same amount of boost, that would be the best way to achieve our goal. I am keep cylinder pressure in mind due to stock sleeves and knowing how the tune looks. The owner said he would rather have more boost and leave the timing alone.
So my question comes down to really what would be safer for the motor? more boost or more timing??? |
it's a general question ,so here is a general opinion.
tune afr's for 12.5 -13:1
tune timing for best output while still avoiding knock (minus ~2 degrees for safety margin) at each boost level
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MrDomino
Joined: 01 Oct 2009
Posts: 188
Location: Indianapolis, IN
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| Posted: Sat Dec 17, 2011 1:48 pm Post subject: |
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Spark timing should be set at MBT timing anways. Advancing it further isn't going to do anything. If spark advance is knock limited then adding more boost is just going to exacerbate things further.
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Myblackhatch
Joined: 04 Oct 2011
Posts: 51
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| Posted: Sat Dec 17, 2011 2:11 pm Post subject: |
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That's what I'm saying. The car is not set to mbt. It has hardly any timing in it. Once they made the power they wanted they stopped.
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stevieturbo
Joined: 29 Aug 2006
Posts: 845
Location: Northern Ireland
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| Posted: Sat Dec 17, 2011 3:16 pm Post subject: Re: Boost vs timing |
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| Roberto Arano wrote: | | Myblackhatch wrote: | So I went to the track last night with a few friends. We all go to support a friend with a local shop and his car.
Now the car is a civic coupe with a ls/vtec setup on boost. Built bottom end but no sleeves. using c16. I didn't personally tune the car but I was there when they did.
to be honest the car has a tone of potential left in the tune. The tuner started tuning the timing map and once it made a certain horsepower the owner of the car was happy and said just leave it how it is. A/f is good and very conservative timing values.
Now last night after going to a test and tune we ran a 10.14 in the 1/4 I think at 139mph. Now we all want to see the car in the 9's and the debate started right there.
I said i think if we added some timing in and left the same amount of boost, that would be the best way to achieve our goal. I am keep cylinder pressure in mind due to stock sleeves and knowing how the tune looks. The owner said he would rather have more boost and leave the timing alone.
So my question comes down to really what would be safer for the motor? more boost or more timing??? |
it's a general question ,so here is a general opinion.
tune afr's for 12.5 -13:1
tune timing for best output while still avoiding knock (minus ~2 degrees for safety margin) at each boost level |
Isnt that very lean for a boosted engine, even on race fuel ? Especially given the performance, sounds like it already runs a lot of boost.
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Myblackhatch
Joined: 04 Oct 2011
Posts: 51
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| Posted: Sat Dec 17, 2011 4:09 pm Post subject: Re: Boost vs timing |
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| stevieturbo wrote: | | Roberto Arano wrote: | | Myblackhatch wrote: | So I went to the track last night with a few friends. We all go to support a friend with a local shop and his car.
Now the car is a civic coupe with a ls/vtec setup on boost. Built bottom end but no sleeves. using c16. I didn't personally tune the car but I was there when they did.
to be honest the car has a tone of potential left in the tune. The tuner started tuning the timing map and once it made a certain horsepower the owner of the car was happy and said just leave it how it is. A/f is good and very conservative timing values.
Now last night after going to a test and tune we ran a 10.14 in the 1/4 I think at 139mph. Now we all want to see the car in the 9's and the debate started right there.
I said i think if we added some timing in and left the same amount of boost, that would be the best way to achieve our goal. I am keep cylinder pressure in mind due to stock sleeves and knowing how the tune looks. The owner said he would rather have more boost and leave the timing alone.
So my question comes down to really what would be safer for the motor? more boost or more timing??? |
it's a general question ,so here is a general opinion.
tune afr's for 12.5 -13:1
tune timing for best output while still avoiding knock (minus ~2 degrees for safety margin) at each boost level |
Isnt that very lean for a boosted engine, even on race fuel ? Especially given the performance, sounds like it already runs a lot of boost. |
I would think so.
You know I was thinking about it and as a tuner, say your customer wants a target horse power that is within reason for there setup. If you run x amount of boost and achieve there goal before you hit mbt. Would you tune for mbt anyway then back the boost down or just stop and leave timing where it is?
I think this might be a better way to ask my question.
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stevieturbo
Joined: 29 Aug 2006
Posts: 845
Location: Northern Ireland
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| Posted: Sat Dec 17, 2011 4:12 pm Post subject: |
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I would use the least amount of boost and optimal timing to achieve their goals.
But when they're so close to a 9....seems silly not to push harder.
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underpsi68
Joined: 21 Dec 2007
Posts: 84
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| Posted: Sat Dec 17, 2011 4:47 pm Post subject: |
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| stevieturbo wrote: | I would use the least amount of boost and optimal timing to achieve their goals.
But when they're so close to a 9....seems silly not to push harder. |
It always seems silly tool you break something. Then you say why did I do that. Lol |
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Turboivo
Joined: 09 Mar 2006
Posts: 671
Location: Bulgaria
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| Posted: Sun Dec 18, 2011 12:54 am Post subject: |
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I'd leave that decision to the owner and his tuner. Otherwise you'll be blamed for every possible fail, no matter is it related to ignition tuning or not.
Also MBT means more cyl pressure too. You're not ensured against problems due to lack of sleevs imho. |
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4SFED4
Joined: 05 Apr 2006
Posts: 119
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| Posted: Sun Dec 18, 2011 7:49 am Post subject: Re: Boost vs timing |
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| Myblackhatch wrote: |
You know I was thinking about it and as a tuner, say your customer wants a target horse power that is within reason for there setup. If you run x amount of boost and achieve there goal before you hit mbt. Would you tune for mbt anyway then back the boost down or just stop and leave timing where it is?
I think this might be a better way to ask my question. |
My .02 would be on the side of tune for MBT and decrease the boost to reach target power and advise the customer as such. |
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TurboNova
Joined: 08 Dec 2004
Posts: 1067
Location: Lake Havasu City, AZ
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| Posted: Sun Dec 18, 2011 9:54 am Post subject: |
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| Myblackhatch wrote: | | That's what I'm saying. The car is not set to mbt. It has hardly any timing in it. Once they made the power they wanted they stopped. |
I think you already know your answer. Tuning to MBT may allow you to run less boost and the car will accelerate quicker. Tuning to knock and backing up 2.... Well you know why that isn't done too.
You have taken the class... There is no guess work on what the timing should be, so make it right.
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APEX Speed Technology
Joined: 13 Nov 2004
Posts: 726
Location: Venice, CA
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| Posted: Sun Dec 18, 2011 10:56 am Post subject: timing |
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I second and third a few of the comments here. The approach the tuner took seems backward. Tune to MBT and limit the power by limiting boost. You can take some timing out to be conservative, but that shouldn't be the way you limit power.
-Neel
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MrDomino
Joined: 01 Oct 2009
Posts: 188
Location: Indianapolis, IN
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| Posted: Sun Dec 18, 2011 12:06 pm Post subject: |
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For the same amount of power you should see similar peak cylinder pressures. However, by not setting timing close to MBT you're going to be torching your exhaust valves. EGTs are going to be really high.
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StantonWarrior
Joined: 10 Dec 2010
Posts: 188
Location: UK
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| Posted: Sun Dec 18, 2011 1:14 pm Post subject: |
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Top and tail of it is, you need to do some logging of your IAT, current knock levels etc, to build up a picture of how the current output is produced.
For sure in any case AFR needs to be adjusted for best power.
MBT is always going to be relative, especially so to 'boost' pressure. So it's always a balancing act. But in any case the least work the turbo is doing, the more stable intake, coolant, residual temps will be. |
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stevieturbo
Joined: 29 Aug 2006
Posts: 845
Location: Northern Ireland
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| Posted: Sun Dec 18, 2011 2:28 pm Post subject: |
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either way, he's gotta go for the 9 lol
I was in the same boat a few years ago. All I wanted was a road car I could drive to and from events that would comfortably run 10's
Then I ran a 10.04 
But whilst I know I can go faster still....I'm not overly keen on breaking stuff to try. But I had to get the 9 in the first place when I was so close.
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9.85 @ 144.75mph
202mph standing mile
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Matt Cramer
Joined: 25 Sep 2007
Posts: 274
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| Posted: Mon Dec 19, 2011 8:33 am Post subject: |
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| Myblackhatch wrote: | | That's what I'm saying. The car is not set to mbt. It has hardly any timing in it. Once they made the power they wanted they stopped. |
Say what?  If you're going to de-tune a turbo motor, do it with less boost, not less timing.
As the others noted, more power is going to mean more mean effective cylinder pressure, and there's the potential here to crack cylinder liners if you turn up the power, regardless of how you do it.
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MrDomino
Joined: 01 Oct 2009
Posts: 188
Location: Indianapolis, IN
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| Posted: Mon Dec 19, 2011 3:06 pm Post subject: |
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I don't know why everyone is so concerned with in cylinder pressures. You're going to fail your exhaust values due to extremely high EGTs before you fail it due to excessive boost pressure which is more or less meaningless unless you have a good idea of what your VE values are.
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StantonWarrior
Joined: 10 Dec 2010
Posts: 188
Location: UK
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| Posted: Mon Dec 19, 2011 3:43 pm Post subject: |
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| And you have practical experience of this?! |
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MrDomino
Joined: 01 Oct 2009
Posts: 188
Location: Indianapolis, IN
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| Posted: Mon Dec 19, 2011 3:51 pm Post subject: |
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Of high EGTs melting exhaust valves? Yes.
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