......Brands Hatch engine 2.0 8v (overbore+longer throw crank)running a TSR 202 (268/272)cam in a BVH on standard plenum but with G60 injectors on a Stealth mapped digi ECU.............now i am led to believe that the compression ratio of these engines remains unchanged at around 10:1 and is not optimum for the cam so could anyone tell me the ideal c/r for this cam and what would be the best way to achieve this c/r..........head off and skim?..how much to take off?......stacked gaskets an option? there is a good old fashioned engine machine shop local to me and i do have access to friendly CNC/Milling machine operators at work so i would be grateful if someone in the know could advise me of the clever stuff regards Tim
10:1 will be fine on that cam spec. The c.r will have gone up anyway due to the std practise of the head & block faces being skimmed, plus if a steel gasket has been used... which is thinner anyway... that will help too. But even if it still is only 10:1 that'll be fine.
....many thanks for an excellent well informed answer as always mr hillclimber on a sidenote does 138bhp @ 5700 and 146lbsft @ 4700 sound about right for my spec?? kind regards Tim oh and ignore my "stacked gaskets" remark as that would clearly do the opposite to skimming
The numbers would be relative to other vehicles tested at that facilty, which may not correlate elsewhere. Bare that in mind. The shape of your torque curve once not skewed is what would be required to analyse.
Some analysis based on what was presented Here are your plots compared to a std ABF Digifant controlled engine also tested Stealth Racing at another time. The ABF vehicle (MK3 Golf) represented in the comparison was known to me and in std form was OK to drive but not as responsive as a Mk3 Golf VR6 vehicle. I would expect that if fitted in a MK2 that the feel of this specific ABF engine would be more MK3 Golf VR6 like. Further to this the suggested 'burst' of torque @6K as measured on this chassis rolls could not be verified on the road using acceleration equipment. Regardless the main point of comparing with your vehicle shows that any inherent errors in process or machine can be assumed to be constant between your test and this vehicle. It is for this reason I suggested to compare against a vehicle tested on this same facility. The plot condensed into spreadsheet Comments on plots The plots suggests, Your modified TSR 2.0 8v does have a small torque advantage between 3600 and 4600rpm when compared to the STD ABF engine's plot. After ~5000rpm the 16v continues to benefit from superior volumetric efficiency and has increasing torque right up to the suggested torque peak of 148lbft@6000rpm. The 2.0 8v is long out of puff. It would take significant modifications to get the 8v to breathe like this stock 16v going by this plot. Real life judgement If the ambients and level of correction between test measurements are similar, I would expect your car to be slightly stronger at WOT in the mid engine speed. In a Golf Mk2 this would feel very lively. However like a strong pulling Diesel it would be soon over at 5-5.5K. There are many many combinations of mapping that would affect the response off WOT and the test does not show this. The plot does not show the effect that the ECU fuel modifications (AFR plot) have had on the wavey WOT torque curve. The torque curve has been altered and even improved with the use of G60 injectors at WOT from the standard profile that you would find on a factory PB engine. If this is now pulling 'strong' if would be quite interesting how it ran before! Comparing the above to a modified 1.8 8v Here is another comparison on the same dyno this time with plots from Alpenweiss2 and his 1.8 shed head w Kent Cam thrown in. This shows the delta between a modified 1.8 8v, your modified 2.0 8v and a std ABF 16v. HTH
.....excellent feedback as always thanks Eddie So as long as i keep it nailed WOT then 3600 to 4600 i will have that standard ABF so long as i bail out @ 5500 before the volumetric efficiency of the valver takes over Prior to mapping it hit 123bhp @ 5200 with 128lbft @ 4400 which was concise with a run on a dyno-dynamics a week before stealth where it hit 127 and 132 at very similar rpms. This would explain how it now pulls much "stronger" and was largely down to cam timing. AFRs were monitored during live mapping via the emulator although i have no print out the killer question would be "could it be improved without substituting ECU/Ignition?".........from what i have researched of other closely specced 2.0 8Vs i suspect this is doubtful Thanks once again for your time on this Eddie
Improvement depends on how the level of spark and fuel control is implemented not only at WOT but at other load/speed areas. This car would have only benefited from fuel adjustments, so in my opinion yes there probably is. As an example my 3A 8v can accelerate from 10 mph in 5th without any det. This is due to mapping not only fuel adjustments but also several iterations on ignition re-profiling while driving. The profile that was developed for my ignition map could not be achieved from using a Digi2 system, where the only option is via dizzy offsetting.
..yeah i understand...i was on the edge of det with 10btdc @2250 with cts unplugged although i have not tried to squeeze any more post remap i do somewhat relish the challenge of squeezing the most from the engine but cant justify the expense of aftermarket for not huge gains......for similar pennies(or less) i could strap an M62 in there with g60 management and double stacked gaskets for more noticeable gains eh
Decent then... Modded airbox? If so I'd expect to see a bit more power with the spec you have...about another 8-10 really.
.......k+n cone shrouded with a decent cold air feed i always expected 145+ myself......so it would be purely down to cam timing then would it as the fuelling has been taken care of with the g60 greens and the remap?? or a tweak on the ignition timing??
Could be anything... I'd guess the fueling is right coming from stealth... and as long as the timing is at least to std spec it should'nt be far off... there's certainly not 10hp there in ignition unless it's radically retarded. Either way, the torque is about right. Does it pull strong?
Could be anything... I'd guess the fueling is right coming from stealth... and as long as the timing is at least to std spec it should'nt be far off... there's certainly not 10hp there in ignition unless it's radically retarded. Either way, the torque is about right. Does it pull strong?
it does pull strong and feels valverish above 3500rpm....similar induction feel to an ABF at this point onwards and flies to the limiter if not wary ignition is currently 10btdc @ 2250rpm with cts unplugged and was close to det before remap only 15000mls so still loosening perhaps?
As this comparison was done with data from the same machine with its specific set of variables, when you say another "8-10" (bhp) would you argee to achieve this it may come with a penalty to torque in the mid range (reduce the torque ramp up and slow the decline at higher rpm = higher bhp reading = less lively to drive)
But it certainly can't feel like an "ABF from 3500 rpm onwards". That would contradict the graph. Perhaps to 5000rpm similar feel to STD ABF engine.
