I've seen builds and cringed. Why replace an OE piston with forged for just a material change? I don't think folk should be allowed to sell a 10:1 comp piston!! - what possible use to they have?
All the ones I have checked have been 45 + or - 1cc. That is close enough on casting variations. The point is the rest of the clearance volume needs to be measured to give an accurate real figure. Back calculating from the factory figure and guesstimating gasket squish is not that accurate when optimising CR. I did that once when younger and dafter and learnt the lesson that the published factory specs are wrong by some margin on the engines I have cc checked.
Possibly yanks using paraffin as fuel, or maybe nitrous? I really have no idea. They also listed turbo ones at 8.5 and 9.0 : 1 that is fair enough.
INFO With regard to OEM figures ... VW`s published output for the standard KR 16v engine was ~ 139bhp / 124lbft wasn`t it ? Several of the recognised tuners that I spoke to when I had mine (new in `91` on a J) stated that these figures were conservative. When my standard (66k)engine was on AMD`s RR with Geof Everett it gave 150bhp / 130lbft, which was no surprise to him. I wonder how / if this relates to the ABF and the outputs / figures being talked about here ?
Depends what final spec engine you are building The US uses lower octane fuel and if you look at alot of there engine specs NASP cars run 9.5 : 1 comp VW 16v engines over there used to run this comp in the 90's i'm sure. I used pistons 10.5 : 1 ABF JE Pistons but my compression is alot higher Havn't seen the 10: comp pistons but there are alot of 11 : 1 comp ABF Pistons other there for sale
Most of the "nominal" ABF engines tested in std mk3 cars ( airbox, exhaust etc) I have tested on the DD 450DS machine achieve around 147-156bhp and 130-138lbft. KRs in mk2 around 130-145bhp. The more miles the engine has to a certain point the less friction and this can be reflected in aftermarket testing. You also have to remember that the "published" are the homolagted results from a 'chosen' engine on a device that may be corrected in DIN or ECE adding further error to aftermarket result. In any case from my aftermarket work the same trend as the 16v engines was observed with other engines, such as VW 140PS TSI MK5 with 30K kms actually testing as 148bhp, Ford Fiesta with 3K miles 1.25 w/60PS testing at 63bhp or 64PS and a 1.2 80PS testing at 85PS. Just hovering around published with this machine. I never expected a 051....103D std head, in combination with other factors to achieve 167lbft to date. Seem to be at a plateau point. But then again I thought as much when it was at 163lbft with a std 051 KR head.
I have a re-mapped ABF ECU which has the matching dyno plot showing a gain of 25BHP midrange and 17ish BHP peak on a certain tuners rollers, on an otherwise standard ABF. Oddly, when I back to back the same modified ECU with the modified EPROM and standard EPROM on Star's rollers, I see a gain of 6-7 BHP peak and 10-12 BHP midrange, on an engine already fitted with modifications already proven to add a few BHP. Power plots lie. Big time. My ABF made 151 BHP standard, on the same dyno my S3 made 208 BHP standard (210 claimed), 911 made 316 BHP standard (320PS claimed) and Lupo GTI made 126 BHP (125 claimed)....so any 16v making 20+ BHP over standard rings alarm bells with me, as it cost me 1000s to find that sort of a gain.
But a delta in torque will lead to a change in measured power at the given rpm point. And if the torque goes up, based on a repeatable baseline then that's that regardless of which machine. To get to 200bhp though that is where money will have to be spent IMO to upgrade certain key components. In other words to get the level torque to hang in + RPM w/o lossing low down response to where it is now = . How much it is = intelligent testing and validation.
Reading this thread with great interest. My engine spec is as follows. 1996 Mk3 golf ABF Block Std VW Crank, balanced with front pulley, flywheel & clutch Integ. Eng. H Beam Rods (Stock ABF spec) Wossner 12.4:1 Forged pistons Stock 051 casting ABF head Newman 288deg cams 11.2mm (I think) lift Stock ABF followers, springs, retainers Stock Pulleys and sprockets Ashley KR 4 Branch header and system DHLA 45s with 38mm chokes Omex 200 Mappable ignition with Ford Edis coil pack This engine did indeed make 201bhp and 159Lbs/ft on Noble Motorsport's dyno, but I was not allowed into the Dyno Cell (H&S) issues, so only got a print out at the end. When run up on Wayne's (Chipwizards) Dyno in early Dec it made 188 and 189 Bhp on two runs, however Wayne picked up on issues with fueling and thought that it could be made to be better & smoother with some changes to the carb set-up. The engine has run for about 1000miles now all track and dyno work as the car is not road legal, so its only ever lived between 5k and 7.5k revs on track. I feel that i'm more likely to believe Wayne's figs over Noble's, think thats a trust thing. I have plans for use of the engine in a new road car project coming soon to a Forum near you... I'm undecided (part due to budget) on weather to run it with Motronic plenum injection with Wayne weaving his magic on OE managment or going Bodies with Omex 600 managment. Seeing gurds make good figs on Plenum/MS i'm unable to decide at the moment.
Excellent info many thanks PAB. Can you shead anymore light on why you think your setup works? any dyno graphs? does it have more to give? and what made you decide to stay with a standard head with your setup? it seems a radical step becuase of all the bottom end work but one I applaud
Not sure i agree totally with this. At the time VW said every Golf Gti 16v will produce 139bhp, this doesn't mean they will produce exactly that but at a minimum. People have had standard engines produce over 150 bhp years after they were made. It depends on too many things, not least how they were run in!!! Gently is not always best from what i understand. A hard (ish) running in is likely to seal the piston rings better giving a higher compression, as i understand it.
Interestingly on that sort of subject. The early vw engines with an 81mm bore used a piston with a diameter of 80.98mm and cylinder bore diameter of 81.01 giving a piston to bore clearance of 0.03mm. Later vw engines with an 81mm bore used a piston with a diameter of 80.965mm and a cylinder bore diameter of 81.01 giving a piston to bore clearance of 0.045mm. This greater size tolerance on the newer engines could be due to a different alloy for the pistons, or the fact that the early engines seem to need 100k miles to run in! Hence why some of the valvers seem to produce more than factory figures after they have been to the moon and back. (dyno lottery taken into account of course).
Yeah, interesting. I personally don't know of any 16v's putting out bad figures even after many miles. My old standard 16v put out 137bhp on vince's rollers after 110,000 miles. Are vince's rollers good, bad or indifferent? Either way vince said the head was well coked up but after wur mod put out 148 bhp.
Surely P+P should be the last thing. If gurds can get 188 from a standard ABF with MS then surely you have got to be looking at better increases from CR increases and valve gear upgrades like already said, then optimsing the map for that set up. Look at pabs for example. Quite a spec but figures whise theres not much in it. Could it be due to carbs rather than inj. Pab do yoh think P+P is the way forward for your build now?
Essthree has a point although I would say "power plots are subject to error". As an operator you have to be on ball to manage these errors to zero. However if one is determined or well resourced, you can find out why or what would influence a machine to have error from reality or a reliable reference. His abilty to reference several different unmodified vehicles and witness them achieve close to OE published numbers, would for a start give me some sort of confidence, pending plot profile in remote data like this. Even more confidence if the vehicle in question is a 16v and was baselined. The spending of thousands though, to achieve 100bhp/litre maybe, but to achieve 160+lbft from std junk yard engine, that is debatable. Yes...VW would have made a marketing statement based on a certified plot generated by engine engineers like this polished one corrected to DIN. This would have been generated from an 16v engine on an engine dyno to certifiable control standards in conjunction with data from other engines on rigs. These engines would have been well run in. The actual curve would have variations from engine to engine in real life and "improve" as the engine became loose, beyond the original cert engine pending in use treatment. If controlled to the same stds and corrections, you would expect a similar result with some variation from car to car if the dyno estimation software is any good. I would not expect a 16v KR with few miles under its belt to achieve 150bhp@6200, with an OE air restrictor in the air box!!! The math with something like that would not agree if it were to drag raced! . It depends on targets time and money. Could also be the next thing or middle mod. But is it required and causing a restriction to targets. Are the aftermarket bench flow numbers coming anywhere close to be achieved compared to actual engine air for target torque? vw_singh's car achieved a peak of 181.5bhp@6000rpm on GS DD450DS device thanks to good bolt on hardware choice and the ability control combustion, to achieve a max effort of 166lbft@5400rpm with 160lbft achieved from 4000-6000rpm. With correlation checks done on the dyno back to new unmodified vehicles, some non vw, and with these vehicles achieving similar curves and peaks within ~6% of OE homologated numbers, be it DIN, ISO, SAE, that are at hand, it is believed that the profiles seen above are what can be expected from a std ABF engine fitted with the same hardware and mapping as this MK1 once steps are taking to confirm baseline transparency. Notice something in the curves though, the plateau suggests something is consistently limited torque, as if the engine was boosted and controlled with a PWM N75. Experiments that involved many mapping sweeps with logging suggests it is an airflow limitation. If it was assumed that mapping was the best it can be, then the air pumping through the engine can related to torque. So perhaps 160+ lbft and the corresponding airflow is near the limits of the std head. We know torque has direct relation to airflow. How much will the std 16v head give? Thing is which one 027, 051/D? Are we talking bhp, torque, actual airflow on from dyno testing compared to flow bench, and what controls will we be working with to ensure transparency in data? In vw_singh’s plots, back in Feb the car first achieved 174bhp@6100rev/min. This was compared to the latest on full ABF 051***373D unit. at WOT 163lbft appears once again, but then the torque surprises with an extra hang on and bump to 166lbft with a negative gradient starting at a higher level on torque or VE! So the other question is more data need to know if the ABF head actually flow more air promote improved filled at higher RPM? It is this higher filling combined with higher engine speed that is part responsible for your numbers. On this dyno the torque level is what is targeted. Bhp so happens to be a by-product of how long in the speed range the level of torque is kept high. I do not know that as fact though...Remember I said power plots are subject to error. To compare the 2 engines and relate to engine airflow for a common study, you really need them on the same reference or use some sort of correlation for transparancy. Plus you look at the whole torque plot for both to see where are the benefits or penalties. So just the peak numbers from both tests are no good for analysis.
FTW and I love it how people will not take risks with Junk Yard Engines but spend 100's on rebuilds that fail within miles... Yes, from another thread the bench flow figures are quoting 190.78BHP. We have seen close to that (and more) from PAB and his high Comp. Very useful info yet again, so the 160+LBFT might be the limit of the standard head, what is the BHP limit? if we shift the peak torque produced by using different methods (cams, CR, inlet track etc) can we move the peak to a higher rpm and increase peak BHP? If so what could we then achive and how will this affect torque throughout the rev range?
PAB another question if you well? What is your inlet track length from valve face to trumpet lip? This is something that will have a major impact on torque; around 350mm + is an optimal figure for around 7000rpm but this is all calculations. Sambo and others have seen good increases in torque by increasing the inlet track as much as possable. This may be one reason why your torque was 159LBFT? - on the 200+BHP run (188BHP run unknow LBFT?) Other reasons might be the cams and the effect the CR has? Great info so far guys lets keep it coming.
Me & Bargate worked on this calculation Brook is 250mm trumpet to back of valve , due to MK1 bonnet restriction Bargate is 300mm trumpet to back of valve, bonnet is not a restriction due to (big hole in bonnet) But both of the above are not standard heads so not relevant to this thread really.
I think PAB may be using the carb inlet manifold with the angled transition from carb to head which is not ideal for flow based on MrH's flow tests, iirc
