What HP can you expect from a unmodded S4?
09-28-2012, 12:13 AM
#31
Nordschleife Master
on an 87 auto I put down 274 rwhp with an X pipe, RMB and a pair of 300cpi cats.
Then I converted it to a manual, added camshafts (advanced to 8 deg), and put down 325rwhp on that same dyno with no other changes other than a tiny bit of tuning though the tune was still "rough"
Then I converted it to a manual, added camshafts (advanced to 8 deg), and put down 325rwhp on that same dyno with no other changes other than a tiny bit of tuning though the tune was still "rough"
09-28-2012, 12:41 AM
#32
Rennlist Member
He has four total Dynojet units on site..its his core biz. A number of us there were kinda thrown back by it as well...but re-ran at a later date in the same range. But there is less 'tune' to set a dynojet, than other types..its just atmospheric correction at that point. Right?
09-28-2012, 02:26 AM
#33
Former Sponsor
Ive thought the same..but this is a highly regarded dyno test & certification facility here in Norcal that the SCCA sends spec cars to be tuned to a HP number, and then sealed.
He has four total Dynojet units on site..its his core biz. A number of us there were kinda thrown back by it as well...but re-ran at a later date in the same range. But there is less 'tune' to set a dynojet, than other types..its just atmospheric correction at that point. Right?
He has four total Dynojet units on site..its his core biz. A number of us there were kinda thrown back by it as well...but re-ran at a later date in the same range. But there is less 'tune' to set a dynojet, than other types..its just atmospheric correction at that point. Right?
I think that any mechanical device that is both hooked to and then has data "translated" by a computer is going to have "correction" factors that can be "altered". I've seen people claiming over 300rwhp, for these cars, in stock trim. I think everyone here knows that there is something wrong, with that.
The other thing that you will "notice" as you make more and more power, that the automatic transmissions are not "linear" in the amount of power that they consume. They become a power "black hole". The efficiency drops like a rock, after a certain point. That torque convertor just gets to the point where it can't transfer any more power from one stator to the other. The internal clutches will also stop "holding" what you are trying to feed them. Like a "slightly weak" clutch in a manual car, you really don't sense that there is all that much being lost....but when you get it to the point where it really works, the difference is huge. I had Andy's transmission in and out about 5 times, for "convertor" changes and internal transmission changes, before I was happy with it. I think I had the valve body out about 20 times, before I was satisfied...and I lost count of how many times I had the pan off to adjust things. Some of the convertors I tried were downright "funny" and got removed after a very short drive around my building.....and they were all convertors from various 928 models. The "transmission" part of this project was seriously the most difficult part of the entire job.....even more than the "oiling" problems and solutions.
I finally had to "bail" and come up with a completely different convertor.
Very time consuming, but very enlightening, also.
09-28-2012, 03:28 AM
#34
What type of refreshers are to be expected to bring an engine close enough to stock without a full rebuild?
I've got 157k on my early 86. I personally think it pulls strong but to be honest, I don't know any better.
I've got 157k on my early 86. I personally think it pulls strong but to be honest, I don't know any better.
09-28-2012, 07:05 AM
#35
Nordschleife Master
928 doesn't have much ring or cylinder wear, so assuming good compression and leak down all that is left is AFR and details like injector having a good spray pattern etc. That is where having a MAF within spec, clean injectors that are flow matched, and no vacuum leaks maybe makes the "difference".
I don't know about the 928, but on many engines they don't make max power for maybe 30k miles as the motor loosens up.
I don't know about the 928, but on many engines they don't make max power for maybe 30k miles as the motor loosens up.
09-28-2012, 07:27 AM
#36
Supercharged
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I'd have to agree that he should have a correctly calibrated machine. Sounds like a valid result, with that knowledge. That's actually only a couple percent more than I'd "plan" on and you had done some Sharktuning, so that makes sense. Good job!
I think that any mechanical device that is both hooked to and then has data "translated" by a computer is going to have "correction" factors that can be "altered". I've seen people claiming over 300rwhp, for these cars, in stock trim. I think everyone here knows that there is something wrong, with that.
The other thing that you will "notice" as you make more and more power, that the automatic transmissions are not "linear" in the amount of power that they consume. They become a power "black hole". The efficiency drops like a rock, after a certain point. That torque convertor just gets to the point where it can't transfer any more power from one stator to the other. The internal clutches will also stop "holding" what you are trying to feed them. Like a "slightly weak" clutch in a manual car, you really don't sense that there is all that much being lost....but when you get it to the point where it really works, the difference is huge. I had Andy's transmission in and out about 5 times, for "convertor" changes and internal transmission changes, before I was happy with it. I think I had the valve body out about 20 times, before I was satisfied...and I lost count of how many times I had the pan off to adjust things. Some of the convertors I tried were downright "funny" and got removed after a very short drive around my building.....and they were all convertors from various 928 models. The "transmission" part of this project was seriously the most difficult part of the entire job.....even more than the "oiling" problems and solutions.
I finally had to "bail" and come up with a completely different convertor.
Very time consuming, but very enlightening, also.
I think that any mechanical device that is both hooked to and then has data "translated" by a computer is going to have "correction" factors that can be "altered". I've seen people claiming over 300rwhp, for these cars, in stock trim. I think everyone here knows that there is something wrong, with that.
The other thing that you will "notice" as you make more and more power, that the automatic transmissions are not "linear" in the amount of power that they consume. They become a power "black hole". The efficiency drops like a rock, after a certain point. That torque convertor just gets to the point where it can't transfer any more power from one stator to the other. The internal clutches will also stop "holding" what you are trying to feed them. Like a "slightly weak" clutch in a manual car, you really don't sense that there is all that much being lost....but when you get it to the point where it really works, the difference is huge. I had Andy's transmission in and out about 5 times, for "convertor" changes and internal transmission changes, before I was happy with it. I think I had the valve body out about 20 times, before I was satisfied...and I lost count of how many times I had the pan off to adjust things. Some of the convertors I tried were downright "funny" and got removed after a very short drive around my building.....and they were all convertors from various 928 models. The "transmission" part of this project was seriously the most difficult part of the entire job.....even more than the "oiling" problems and solutions.
I finally had to "bail" and come up with a completely different convertor.
Very time consuming, but very enlightening, also.
09-28-2012, 11:04 AM
#37
I wish I would have dynoed mine stock before I modded it just to see the difference. Over the one winter I did a top end refresh, plugs, wires, caps, rotors, supercharger and x pipe all at once! I saw a bit of an increase! 
09-28-2012, 11:27 AM
#38
Drifting
Thread Starter
Wait a minute, aren't you the same guy who's been saying that he wasn't going to dyno his car because he didn't care about numbers?
I'm not giving you a hard time (much), and please don't dump a pile of crap all over me again. I'm just saying that your sudden interest in horsepower numbers is kind of amusing.
It doesn't matter what people "think" horsepower is, it is something that can be measured. The factory spec for the S4 (brand-new everything) was 316 bhp, that is SAE horsepower measured at the crank. If you take that number and figure 15% loss with a 5-speed that gives you around 270rwhp, and a Rogerbox with 18% loss would be around 260rwhp, that's rear-wheel hp on a chassis dyno with SAE correction. Which is pretty consistent with what's been reported here and elsewhere. So I think the factory number for the S4 is pretty good, on average. (GT's are different, but that's not what you asked).
That's for a new car. A 25-year-old car will be lower, depending on what sort of condition it is in. "Refreshing" the things that need refreshing is helpful, but doesn't add any horsepower-- it just gets you back towards where the car started. And don't overlook the MAF, it is the key component for fueling.
As for power-adders, don't believe everything that you read. Many folks report big numbers for x-pipes, but remember that they are swapping cats as well as adding the crossover. An x-pipe with new 100-cell cats (or no cats) will certainly outperform a set of melted, clogged factory cats. I do not know of anyone who has done the apples-to-apples comparison and just added the x-pipe without changing cats. I am not saying that x-pipes don't add hp, they do. But doing a proper before/after is not simple.
Will you be at Sharktoberfest? I think there is a dyno in Anaheim.
I'm not giving you a hard time (much), and please don't dump a pile of crap all over me again. I'm just saying that your sudden interest in horsepower numbers is kind of amusing.
It doesn't matter what people "think" horsepower is, it is something that can be measured. The factory spec for the S4 (brand-new everything) was 316 bhp, that is SAE horsepower measured at the crank. If you take that number and figure 15% loss with a 5-speed that gives you around 270rwhp, and a Rogerbox with 18% loss would be around 260rwhp, that's rear-wheel hp on a chassis dyno with SAE correction. Which is pretty consistent with what's been reported here and elsewhere. So I think the factory number for the S4 is pretty good, on average. (GT's are different, but that's not what you asked).
That's for a new car. A 25-year-old car will be lower, depending on what sort of condition it is in. "Refreshing" the things that need refreshing is helpful, but doesn't add any horsepower-- it just gets you back towards where the car started. And don't overlook the MAF, it is the key component for fueling.
As for power-adders, don't believe everything that you read. Many folks report big numbers for x-pipes, but remember that they are swapping cats as well as adding the crossover. An x-pipe with new 100-cell cats (or no cats) will certainly outperform a set of melted, clogged factory cats. I do not know of anyone who has done the apples-to-apples comparison and just added the x-pipe without changing cats. I am not saying that x-pipes don't add hp, they do. But doing a proper before/after is not simple.
Will you be at Sharktoberfest? I think there is a dyno in Anaheim.
Last edited by rgs944; 09-28-2012 at 11:49 AM.
09-28-2012, 12:27 PM
#40
Rennlist Member
I have not had my 86.5 auto on a dyno but I know it puts out 310-325 ‘cause that’s what the PO said it would do with the RMB and after market chips he installed. 
09-28-2012, 12:27 PM
#41
Rennlist Member
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I likely will never dyno because I am worried about modern steet drivabilty over peak rpm range HP
Not trying to start anything. The whole dyno thing is rife with variables. Following all of this with interest. Victor has generated 3 or is it 4 threads indirectly?
09-28-2012, 12:36 PM
#42
Drifting
Thread Starter
To put it simply. No, dyno #'s are not real important to me. But if someone asks what kind of power the engine has I want to be able to give them an honest and close estimation.
09-28-2012, 01:02 PM
#43
Drifting
"As for power-adders, don't believe everything that you read. Many folks report big numbers for x-pipes, but remember that they are swapping cats as well as adding the crossover. An x-pipe with new 100-cell cats (or no cats) will certainly outperform a set of melted, clogged factory cats. I do not know of anyone who has done the apples-to-apples comparison and just added the x-pipe without changing cats. I am not saying that x-pipes don't add hp, they do. But doing a proper before/after is not simple. "
Hey Jim....I do. Let me know if you would like to see the dyno sheets. I have hundreds from 85-86's, S4's and GTS's. I compared my crossover to Louie's and stock with and without cats, every option available including gutted factory cats. I can tell you the losses with each type of catalytic converter and cell density including the ones we had manufactured for our systems. The majority of my testing was on the same dyno, same day without even unstrapping the car. Just jacking it up and swapping while hot. No tuning was done to optimize any configuration either. When I tested against the factory cats I used the best set I had available out of at least a dozen sets unlike someone in across the pond...they started with a 240rwhp GT!
Hey Jim....I do. Let me know if you would like to see the dyno sheets. I have hundreds from 85-86's, S4's and GTS's. I compared my crossover to Louie's and stock with and without cats, every option available including gutted factory cats. I can tell you the losses with each type of catalytic converter and cell density including the ones we had manufactured for our systems. The majority of my testing was on the same dyno, same day without even unstrapping the car. Just jacking it up and swapping while hot. No tuning was done to optimize any configuration either. When I tested against the factory cats I used the best set I had available out of at least a dozen sets unlike someone in across the pond...they started with a 240rwhp GT!
09-28-2012, 01:40 PM
#44
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