I had tracked down some Bertils parts to a UK motorsport parts dealer inc. rocker cover, throttle bodies and dry sump but he wanted too much for them as they were all a bit tatty and incomplete. Went to Germany in the end. I run a set of Spiess throttle bodies on my 8v similar to the mechanical injection motor above and they are very nice quality. Full taper from the mouth down to the head, hand finished and all expertly cast and accurate. I read on the SBD site that full taper 45mm throttle bodies will flow more that a set of 48's. As I recall the Spiess ones are 46.5mm so being full taper flow well. The problem with them is they are too long really as they are designed for F3 engines that make more torque than power due to the restricted air. I have bespoke trumpets fitted to keep the length down and get over 220bhp at around 7500rpm so good enough for an 8v. I just like them as they have history to them as much as anything. They were originally on a 91 Dallara F3 car, a similar car (not the exact same one) car that Michael Schumaker won the F3 World Championship with in 1990. Gives the engine bay a bit of interest
I've been meaning to post a bit of info about my 8v for a while, as there doesn't seem to be many road going tuned 8v's nowadays. Thought some of you might find this useful. 176bhp@5750rpm 196lbft@2400rpm (approx) Is there any more possible from this engine? Schrick 304 cam perhaps? Below is the recently rolling road run. TSR 2008cc short block Custom spec Dave Crisell/Grant Motorsport head 41mm inlet, 36mm exhaust Grant Motorsport fast road cam R1 bike carbs
Strong curve, but the figures are waaaaaay over the top. Totally impossible to achieve 196ibft of torque at any rpm from an 8v...and most 16v's of any make..2ltr or under....let alone down at that low rpm. Depending on the actual cam used peak power could be pushed further up the rev band with ease...I'd guess the current cam is something like a 272-276 duration. To go bigger the C.R needs to be known and adjusted to suit a cam change subject to what it is now...and find a rolling road that gives real figures at the wheels and a realistic flywheel conversion.
I am inclined to agree with Jason regarding the how realistic is the reading. In order to understand how the engine performs in reality, my questions relate to this qoute, "112bhp -> 114bhp -> 124bhp > 146bhp -> 176bhp ->". Were these measurements all taken at the same dyno place? And do you have the plot overlays to show the improvements from base 112bhp to this test? I should also point out, for a performance engine ( numbers aside), the torque profile peaks far too low @ ~2400rpm, which suggest diesel like characteristics for in gear acceleration*. Your experience from driving the car I am sure, might suggest otherwise. If that were the case, then it would mean the torque profile shown here is actually incorrect and invalidates the reading as engine torque is directly proportional to axle torque and vehicle acceleration force. *I would expect a car like yours, with an engine like that, to have maximum acceleration at 4-4.5krpm. This equates to maximum engine torque at 4-4.5krpm as well.
Agree with the comment about the torque. I'm taking the torque value with a healthy pinch of salt, but I trust the bhp to be accurate plus/minus a few bhp, as the engine has recently shown 150bhp@wheels on a separate dyno. I'm still running a std 020 'box and have previously measured 30.4 bhp transmission loss at stealth racing.
112/114/124 were all at the same dyno, but unfortunately no longer available. 146 was at stealth running std k-jet, we saw just short of 150bhp on the dyno but tweaked the vernier pulley a bit to get a better curve lower down. The 176 was on different dyno with a custom ported inlet manifold and r1 bike carbs and new 4branch manifold. On the road a huge difference in driving feel between K-jet and the bike carbs. Day and night. that's exactly what stealth dyno showed when on k-jet. But now with the bike carbs, the engine picks up so much quicker with a rock solid idle, none of that usual lumpy k-jet experience, incredible difference.
Ah. Test 1-3 compatible - (dyno unknown) Test 4 different dyno - Stealth (Sun Ram 12) Test 5 different dyno - Ricci Concept ( unknown dyno) Your feedback suggests and even faster car than after test 4, meaning test 5 maybe is likely to be a false reading, particularly as 196lbft is the torque generated by a lightly turbocharged engine. What was you redline by the way? My suggestion would be to at least retest at Stealth Racing ( if possible), with car as last tested at Ricci, The you would have at least one older test to reference. We recently tested a Fully built GMS 2E lump + cam CR etc at the ClubGTI/Badger 5 dyno day and while is was certainly stronger than a stock 8 GTI, tested on the same day, it was not over 150bhp on Bill's rolls.
Limiter kicks in at 6300rpm Agree, wish Stealth was a few hours closer. Assume that was on k-jet, rather than bike carbs?
No on Digifant. Running on carbs would have helped just a tad but you would still be clipped by the ignition system.
Certainly closer to the truth than the "quote me happy" rollers. I tend to see around a 15-17% transmission loss from engines that have been run on the engine dyno then on the rollers, so around 25hp from a 170 hp engine should make around 145 at the wheels...which they do. I just did a 2ltr PB based engine with a 276 cam and 42/33 head on digi...made high 120's at the wheels, so around low 150's at the flywheel @ 6000, peak torque at 4,500 - 155ibft with around 120 ibft @ 3000. That engine would make around another 10hp peak on open induction. If you fancy a trip South Lhasa we'd gladly run it for you.
Also on open induction, I would expect in the example you gave to have say not only 10bhp more but also shift the rpm right by ~500 rpm or so. Torque would also drop down about 5-8 lbft and also shift higher in the rpm band. Still not 176bhp@5700rpm. The plot above looks like a stock profile amplified somewhat. Maybe a candidate for your dyno day
I'm game! Yes it would hang on a little better too...the digi car drops 10hp @ 6500, though on the cam used it would only hang on a couple hundred rpm more before dropping.
