Dummies ?
- Thread starter teamzr1
- Start date
CaptainK
CCCUK Member
I've had most of my interesting cars on the rollers over the years, thankfully no issues.
From memory:
1993 205 GTi 1.9 CAT model ran 96bhp fly. Should have been 122. Knew there was summat wrong with it. I shoved in a GTi-6 engine later with throttle bodies and that ran about 186bhp then. Can't remember wheels figures for this though as it was tested circa 2010.
1994 FTO: 196bhp fly / 164bhp wheels. 197bhp fly is standard for the car, so running spot on. Strangely this sticks in my mind, despite it being done around 2005-2006 ish.
1968 Vette: was around 180bhp before tuning, then jumped to about 250bhp afterwards, presumably flywheel figures as wasn't told otherwise. I knew the car wasn't setup right, and just goes to show carb tuning is a must - no other changes/mods were made to get that increase, just setup the new carb that was installed a few months back to replace the one the car came with that was even worse running. Tested about 2 years ago.
From memory:
1993 205 GTi 1.9 CAT model ran 96bhp fly. Should have been 122. Knew there was summat wrong with it. I shoved in a GTi-6 engine later with throttle bodies and that ran about 186bhp then. Can't remember wheels figures for this though as it was tested circa 2010.
1994 FTO: 196bhp fly / 164bhp wheels. 197bhp fly is standard for the car, so running spot on. Strangely this sticks in my mind, despite it being done around 2005-2006 ish.
1968 Vette: was around 180bhp before tuning, then jumped to about 250bhp afterwards, presumably flywheel figures as wasn't told otherwise. I knew the car wasn't setup right, and just goes to show carb tuning is a must - no other changes/mods were made to get that increase, just setup the new carb that was installed a few months back to replace the one the car came with that was even worse running. Tested about 2 years ago.
Roscobbc
Moderator
Dyno tuning at the flywheel is generally (and understandably) about looking for maximum HP and TQ figures and the rpm those figures are achieved (at wide open throttle).
The only adjustments generally made whilst on the dyno will be to change up/down carb main jets if A/F ratio shows a less than ideal figure. Timing will be adjusted to help maximise these figures.
Dyno time isn't cheap and once the engine has been 'proved' and maximum figures recorded the engine will generally be pulled off the dyno ready for the next customers engine. When I had my new engine 'built-up' much the same procedure above followed.
We all hear the pub chat about what people have done to their engines and what HP figures they think (hope?) their engine is putting-out, generally quoting makers figures.
I had spent many thousands of pounds on components and
A. I wanted to see the engine was running correctly. (Logic being that if any 'issues' ocurred during the test the guy who built the engine was in charge of the test and would hardly be in a position to argue about remedial action)
B. wanted to know the HP/TQ figures.
Ideally wanting a modern day, but tractable and street friendly equivalent to the output figures of GM's legendary L88 427 with about 1.25hp per cubic inch (and hopefully 600hp) I didn't initially achieve that hoped-for figure (so 515 hp @5950 and 549 @ 3800 rpm)......more about that later.
The new engine ran fine once installed in the Vette but driveability off idle was really poor.......and the reason?......primary main jets were far too small. Secondary's were perhaps larger than ideal (but who uses full open throttle for street driving). So the primaries were gradually increased by about 7 or 8 sizes and the largest primary accelerator pump 'squirters' were ultimately used to 'cover' off-idle bogging.
Only then did it become street driveable. Guessing that when on dyno running wide open throttle fueling was 'enhanced' by larger secondary main jets.
The 'new' engine had extremely high oil pressure (90 psi and literally 'off the clock' when cold). A couple of big end bearing clearances must have been too 'tight' and a subsequent failure and big end bearing brake-up meant a trip to return the engine to John Sleath for a bottom end rebuild.
John set the engine up on his dyno once more, and surprisingly apologised that his previous dyno figures were incorrect. He hadn't 'dialled-in' the correct compensation figures for air temperature and density. The 'new' dyno run now saw 570 hp @ 5950rpm and 606 ft/lbs tq @ 3900 rpm.......so still not quite the 600+ hp I had wanted but the 606 tq figure was perhaps a more accurate indication of power output.........and amazingly fuel economy even with a 950cfm double pumper carb was still fractionally better than the stock 390hp 427.
The only adjustments generally made whilst on the dyno will be to change up/down carb main jets if A/F ratio shows a less than ideal figure. Timing will be adjusted to help maximise these figures.
Dyno time isn't cheap and once the engine has been 'proved' and maximum figures recorded the engine will generally be pulled off the dyno ready for the next customers engine. When I had my new engine 'built-up' much the same procedure above followed.
We all hear the pub chat about what people have done to their engines and what HP figures they think (hope?) their engine is putting-out, generally quoting makers figures.
I had spent many thousands of pounds on components and
A. I wanted to see the engine was running correctly. (Logic being that if any 'issues' ocurred during the test the guy who built the engine was in charge of the test and would hardly be in a position to argue about remedial action)
B. wanted to know the HP/TQ figures.
Ideally wanting a modern day, but tractable and street friendly equivalent to the output figures of GM's legendary L88 427 with about 1.25hp per cubic inch (and hopefully 600hp) I didn't initially achieve that hoped-for figure (so 515 hp @5950 and 549 @ 3800 rpm)......more about that later.
The new engine ran fine once installed in the Vette but driveability off idle was really poor.......and the reason?......primary main jets were far too small. Secondary's were perhaps larger than ideal (but who uses full open throttle for street driving). So the primaries were gradually increased by about 7 or 8 sizes and the largest primary accelerator pump 'squirters' were ultimately used to 'cover' off-idle bogging.
Only then did it become street driveable. Guessing that when on dyno running wide open throttle fueling was 'enhanced' by larger secondary main jets.
The 'new' engine had extremely high oil pressure (90 psi and literally 'off the clock' when cold). A couple of big end bearing clearances must have been too 'tight' and a subsequent failure and big end bearing brake-up meant a trip to return the engine to John Sleath for a bottom end rebuild.
John set the engine up on his dyno once more, and surprisingly apologised that his previous dyno figures were incorrect. He hadn't 'dialled-in' the correct compensation figures for air temperature and density. The 'new' dyno run now saw 570 hp @ 5950rpm and 606 ft/lbs tq @ 3900 rpm.......so still not quite the 600+ hp I had wanted but the 606 tq figure was perhaps a more accurate indication of power output.........and amazingly fuel economy even with a 950cfm double pumper carb was still fractionally better than the stock 390hp 427.
CaptainK
CCCUK Member
Good news on yours Roscobbc on finding more power from it (but eek on needing a rebuild so soon after building it). My carb setup stuff I have no idea what dark magic carb tuning is, but it did involve new jets and some other stuff. I did say to them I wasn't looking for "max power" figures, just for it to run properly as it was a pig from idle to around 1800rpm, and wouldn't really rev further than 3500rpm, and backfired on the overrun when you let off the throttle at motorway speeds.
The actual figures the rolling road gave me is irrelevant to me - upon picking up the car it was SO much better to drive at slow speeds and will now rev beyond 3500rpm when I want it to (hardly ever to be honest). It was like chalk and cheese the driveability of it, and felt like a different car - evidenced by the torque graph which shows an almost flat "line" of max 300lbs-ft across most of the rev range (well, you know it fluctuates up and down a bit over the rev range, but its peak was 300, and least was 290 I think). Trying to remember from memory is hard, but you get the gist.
As for my other cars I've tested - I knew my old original 1.9 205 GTi engine started to have issues as it was fine at low to mid revs, but struggled to rev that high - hence the lower than expected max BHP figures. Driving "normally" it was fine though and felt quite "torquey". The FTO has always been consistent in its driveability all the time I've had it - low torque engine, "line" on graph again stays mostly flat around the 120lbs ft figure. But its a Jap high revving variable valve timing engine, so its running as expected. Neither of these two cars went in for dyno tuning - I just had them tested for fun and because I'm interested in things like that.
The actual figures the rolling road gave me is irrelevant to me - upon picking up the car it was SO much better to drive at slow speeds and will now rev beyond 3500rpm when I want it to (hardly ever to be honest). It was like chalk and cheese the driveability of it, and felt like a different car - evidenced by the torque graph which shows an almost flat "line" of max 300lbs-ft across most of the rev range (well, you know it fluctuates up and down a bit over the rev range, but its peak was 300, and least was 290 I think). Trying to remember from memory is hard, but you get the gist.
As for my other cars I've tested - I knew my old original 1.9 205 GTi engine started to have issues as it was fine at low to mid revs, but struggled to rev that high - hence the lower than expected max BHP figures. Driving "normally" it was fine though and felt quite "torquey". The FTO has always been consistent in its driveability all the time I've had it - low torque engine, "line" on graph again stays mostly flat around the 120lbs ft figure. But its a Jap high revving variable valve timing engine, so its running as expected. Neither of these two cars went in for dyno tuning - I just had them tested for fun and because I'm interested in things like that.
Chuffer
CCCUK regional rep
Going back about 20 years I had a 1995 Toyota MR2 that had Superchipped , K &N Induction system , and all properly set up . Fitted Koni adjusatble shox and lowered too . The guys dyno`d it at 192 .1 hhp at the wheels . Like you say Captain , funny how yoy remember this stuff innit ?? It was a real Pocket Rocket and a great fun on a couple of track days I did . I gave it to my dearly beloved as a daily driver when I bought my Marcos Mantara V8 as new fun car . We kept `Beanie` as she called it for 11 years . It was like a family pet and never missed a beat other than the the usual maintenance jobs .
Totally with you on carb tuning being a must . The C3 was totally transformed when I junked the old 750cfm Holley , ahd a new 650cfm Edelbrock installed and properly tuned and the timing set up right by Chevy engine specialists and drag racers . It wasn`t dyno tested so do`nt have a clue about bhp although the guys did say "the engine was getting a bit tired " but then so am I some days !! However , the first test drive made it feel like a different car .
