GS1100 Dyno Results Analysis

[davel]

fwiw,

Here are dyno results of a GS1100ES from Cycle Mag April 1983

[davel]

Here are dyno results from my stock 82 GS1100EZ with 40,000mile. It was tested at sea level on 01-06-2010

http://www.thegsresources.com/_forum/showthread.php?t=156060

This chart lists torque and RPM for both tests.

Note the maximum difference between these two test (taken on different dynos 27 years and 40,000 miles apart) is 1 lb-ft...Both engines peak at 62lbft and 91hp.

It surprised me too. Uncanny.

[posplayr]

fwiw,

Here are dyno results of a GS1100ES from Cycle Mag April 1983

That test was for an 83 GS1100ESD which according to the article I posted from Cycle World was 108 hp, while yours EZ was supposedly 105 hp. So we would expect a higher output than the 91 rwhp closer to 94 hp.

There is a Cycle World April 82 article which claimed a 108 hp for the EZ and recorded 92.6 hp. If we assume the spec was actually 105 and not 108 then we have a 3 hp spec deficient EZ posting 1.5 hp better than the ESD. So we have to be careful of hanging our hat on only 1 or 2 measurements.

It seems we are dealing with +/- 1 or 2 hp variation due to the bike to bikes variation and +/- 1 or 2 hp due to Dyno accuracy so it is hard to make a judgment based on one set of data even though you would appear to have the same results.

[Mysuzyq]

That test was for an 83 GS1100ESD which according to the article I posted from Cycle World was 108 hp, while yours EZ was supposedly 105 hp. So we would expect a higher output than the 91 rwhp closer to 94 hp.

There is a Cycle World April 82 article which claimed a 108 hp for the EZ and recorded 92.6 hp. If we assume the spec was actually 105 and not 108 then we have a 3 hp spec deficient EZ posting 1.5 hp better than the ESD. So we have to be careful of hanging our hat on only 1 or 2 measurements.

It seems we are dealing with +/- 1 or 2 hp variation due to the bike to bikes variation and +/- 1 or 2 hp due to Dyno accuracy so it is hard to make a judgment based on one set of data even though you would appear to have the same results.

IMHO, the hp difference between both years is really splitting hairs & a moot issue on the street...having ridden both bikes in various states of tune, I can honestly say there isn't any discernible 'seat of the pants' difference from one year to another, definitely no noticeable difference in performance like when stepping up to an 1150 with it's significant difference in hp. 3 hp is well within the normal variation parameters for 2 stock bikes of the same year, or even the same bike on two different days, or two different dynos. The difference on paper is small enough that rider size & weight are going to be a bigger factor in the real world. The most significant improvement was the welded crank for '83, which instantly makes it a better choice, esp. if performance mods are planned.

[posplayr]

IMHO, the hp difference between both years is really splitting hairs & a moot issue on the street...having ridden both bikes in various states of tune, I can honestly say there isn't any discernible 'seat of the pants' difference from one year to another, definitely no noticeable difference in performance like when stepping up to an 1150 with it's significant difference in hp. 3 hp is well within the normal variation parameters for 2 stock bikes of the same year, or even the same bike on two different days, or two different dynos. The difference on paper is small enough that rider size & weight are going to be a bigger factor in the real world. The most significant improvement was the welded crank for '83, which instantly makes it a better choice, esp. if performance mods are planned.

Well this really is not about how fast either bike is, but what loss factor to apply in developing a Dyno estimate. For some of the same reasons you mention it will vary bike to bike, dyno to dyno.

[Mysuzyq]

Well this really is not about how fast either bike is, but what loss factor to apply in developing a Dyno estimate.

WRT that, I agree that 15% is a good estimate. FWIW, most magazines also use 15% to guesstimate wheel hp of new models (from given factory figures), before actually getting the chance to dyno-test them.

[posplayr]

WRT that, I agree that 15% is a good estimate. FWIW, most magazines also use 15% to guesstimate wheel hp of new models (from given factory figures), before actually getting the chance to dyno-test them.

Good to hear; I did not want to be guilty of just propagating a old wives tale.

[headsbikesmopars]

MYSUZYQ,

The '83 GS1100 was noticeably stronger than the earlier models just as the '81 was much stronger than the '80 models. The '83 had a much more efficient less restrictive redesigned air box than the previous models, and a VERY good set of cams. The '83 cams were by far the best of the GS1100 series. I have seen over 135 hp using the '83 cams a 4 into 1 , set of 36 cv's form the 1150 and a nice street head with a clean up and a good bowl port much like Jim's . Nothing radical or racy. The '83 was the best of the GS1100 series and the 1150's were a step up from the '83 1100. Suzuki should have used the 36 cv's on the '83 models. JMHO.

Terry

[Mysuzyq]

MYSUZYQ,

The '83 GS1100 was noticeably stronger than the earlier models just as the '81 was much stronger than the '80 models. The '83 had a much more efficient less restrictive redesigned air box than the previous models, and a VERY good set of cams. The '83 cams were by far the best of the GS1100 series. I have seen over 135 hp using the '83 cams a 4 into 1 , set of 36 cv's form the 1150 and a nice street head with a clean up and a good bowl port much like Jim's . Nothing radical or racy. The '83 was the best of the GS1100 series and the 1150's were a step up from the '83 1100. Suzuki should have used the 36 cv's on the '83 models. JMHO.Terry

Terry, I'm aware of all the differences between the two years...also of all the potential that exists for modding for more hp.
I posted about my riding impressions from putting miles on both bikes, often back to back.....I don't know if I would describe the 3 hp difference at the crank, or the difference in torque as translating to 'noticeably stronger' on the street. Again, this could simply be due to differences in condition/set-up from bike to bike and the fact that mileage on both was vastly dissimilar.
What you posted might be more the case in comparing both bikes straight off the showroom floor, but in the real world, with any mods at all thrown in the mix, all bets are off, IMHO.
I agree that the '83 was the best of the series, but the reason I cited was more the reinforced crank. Also agree with the comment on the 36mm carbs.....FWIW, my '82 simply modded with 36 mm BDST carbs, degreed stock cams and 4X1 Wolf pipe was able to leave the '83, (modded with pods, rejetted stock carbs and 4X1 pipe) in any & all situations.

[headsbikesmopars]

Terry, I'm aware of all the differences between the two years...also of all the potential that exists for modding for more hp.
I posted about my riding impressions from putting miles on both bikes, often back to back.....I don't know if I would describe the 3 hp difference at the crank, or the difference in torque as translating to 'noticeably stronger' on the street. Again, this could simply be due to differences in condition/set-up from bike to bike and the fact that mileage on both was vastly dissimilar.
What you posted might be more the case in comparing both bikes straight off the showroom floor, but in the real world, with any mods at all thrown in the mix, all bets are off, IMHO.
I agree that the '83 was the best of the series, but the reason I cited was more the reinforced crank. Also agree with the comment on the 36mm carbs.....FWIW, my '82 simply modded with 36 mm BDST carbs, degreed stock cams and 4X1 Wolf pipe was able to leave the '83, (modded with pods, rejetted stock carbs and 4X1 pipe) in any & all situations.

I don't believe the 3 hp rating between the '83 and earlier models. The cams alone were worth twice that. Suzuki rated Katana 1100 at 111 hp and that was the same engine. In like manor, in 1970 Chevrolet rated the Lt1 at 370 horse in the Corvette and the same engine in the camaro at 360 horse. Also the solid lifter 396 was rated at 425 in the Vette and 375 in the Chevelle , same reason. To not upstage the Corvette. Anyway I guess we will have to agree to disagree on this one.

[posplayr]

I don't believe the 3 hp rating between the '83 and earlier models. The cams alone were worth twice that. Suzuki rated Katana 1100 at 111 hp and that was the same engine. In like manor, in 1970 Chevrolet rated the Lt1 at 370 horse in the Corvette and the same engine in the camaro at 360 horse. Also the solid lifter 396 was rated at 425 in the Vette and 375 in the Chevelle , same reason. To not upstage the Corvette. Anyway I guess we will have to agree to disagree on this one.

Terry,
So what are you figuring the true ratings would have been for the following years?

80 1100ET 103 hp?
81 1100EX 105 hp
82 1100EZ 108 hp
83 1100ED/ESD/SD 111 hp
84 1150E 119 hp
85 1150E 124 hp

What is funny is that the CycleWorld tests showed the 81 bike being about as if not faster than the 82 and showing higher dyno numbers.
CW discussion here:

http://www.thegsresources.com/_forum/showpost.php?p=1330545&postcount=10

Jim

[Mysuzyq]

I don't believe the 3 hp rating between the '83 and earlier models. The cams alone were worth twice that. Suzuki rated Katana 1100 at 111 hp and that was the same engine.

Yes, I was going by the 111 hp published by the factory for both the '83 Kat & ED....and the 108 given for the previous year EZ. I would say the factory ratings for both years (or rather, the hp difference between them) are accurate, esp. if one looks at the negligible difference in hp/torque curves in several magazine actual dyno tests (of both models), and also the very similar performance figures (top speed etc) as tested. Glad you are taking this in the proper spirit.... I'm not trying to be argumentative, as frankly, this is like splitting hairs, as I said earlier.
To Jim's point, I have not ridden any of the earlier rectangular-headlight 1100EX bikes, but my friend who owned the '83 1100E had one of those for a short while that he rode on the street and occasionally dragged. I remember him commenting too, that the bike felt pretty strong, and not as significantly weaker as one would expect, given the almost 10 hp deficit (according to some published specs) to his ED. Don't know what to make of that, as the bike was largely stock.

[headsbikesmopars]

Jim,
I feel the '80 was more around 100 hp. That is what the Euro model was rated and I don't think there was any difference between that engine and the us model..except the us model carbs was leaned out compared to the Euro carbs. So..the us '80 model could have been even less than 100, not much but a couple maybe. I feel the other ratings were very close, would'nt argue with the 105 for the '81 or 108 for the '82 it was a good performer and I don't doubt the 111 for the '83 except it might have even a little stronger than that 112-113 would be believeable. The '84 1150 was rated at 119 while the '85 1150 was 124..I feel the 1150 was no more than 10 hp better than the '83 1100. JMHO as always. The '81 bike that was used for the road tests was no doubt a 'ringer' most '81's I have seen at the drag strip and on the street would run with the '82 models but not the '83's. Most of the '81's were in the upper 11's , 11.80 range. I rode a friends '82 GS1100 down the strip once (only time I was on it) and went 11.74 with my 210lbs. my '81 all stock went a best 11.78 but was 11.83 just about every time out. A friends '83 would do 11.60 range and a '85 1150 (same guy that had the '82) would do 11.50 all stock. We were at elavation too so the times would have been better at a low elavation or better yet sea level. But the comparo to the ET's with the different model years was interesting. This was back in the mid eighty's...great times they were. Another thing,. no matter what the mags would print the GS1100's were KING at the strip. until the GSXR's came out. Blew off many V maxes and those Honda Magna's they were easy. Leaving the line I would NEVER see them again until coming down the return road to the pits. LOL, I miss those days. VERY good topic indeed. Thanks.

Terry

[headsbikesmopars]

Oh, just as a side note, I also had a '73 Kawaski H2 750 that I ran at the strip. I Raised the Exhaust port 4 mm amd machined the intake side of the piston (skirt) 4 mm ,raised the transfer ports 2 mm and that is all along with a set of Gast race chambers and a set of 34 mm mikuni power jet carbs. I built the wheelie bars. That bike ended up going 10.50 !! with me on it..with no air shifter. That bike was alot of fun. I know 10.50 isn't a world beating time but for back in the day and so little work to a 750..well it was a great little bike to try to stay on. Had to be an acrobat to ride it, LOL. Just wanted to share this memory..that bike is in Finland now.

Terry

[posplayr]

Jim,
I feel the '80 was more around 100 hp. That is what the Euro model was rated and I don't think there was any difference between that engine and the us model..except the us model carbs was leaned out compared to the Euro carbs. So..the us '80 model could have been even less than 100, not much but a couple maybe. I feel the other ratings were very close, would'nt argue with the 105 for the '81 or 108 for the '82 it was a good performer and I don't doubt the 111 for the '83 except it might have even a little stronger than that 112-113 would be believeable. The '84 1150 was rated at 119 while the '85 1150 was 124..I feel the 1150 was no more than 10 hp better than the '83 1100. JMHO as always. The '81 bike that was used for the road tests was no doubt a 'ringer' most '81's I have seen at the drag strip and on the street would run with the '82 models but not the '83's. Most of the '81's were in the upper 11's , 11.80 range. I rode a friends '82 GS1100 down the strip once (only time I was on it) and went 11.74 with my 210lbs. my '81 all stock went a best 11.78 but was 11.83 just about every time out. A friends '83 would do 11.60 range and a '85 1150 (same guy that had the '82) would do 11.50 all stock. We were at elavation too so the times would have been better at a low elavation or better yet sea level. But the comparo to the ET's with the different model years was interesting. This was back in the mid eighty's...great times they were. Another thing,. no matter what the mags would print the GS1100's were KING at the strip. until the GSXR's came out. Blew off many V maxes and those Honda Magna's they were easy. Leaving the line I would NEVER see them again until coming down the return road to the pits. LOL, I miss those days. VERY good topic indeed. Thanks.

Terry

Thanks Terry
I'll see if I can make a little more sense out of the data.
Jim