turbogrill Posted June 30, 2017 Share Posted June 30, 2017 More headwork is not a bad idea either, but I think ultimately that cam will hold you back from the highest top end numbers you can get out of that motor. I had a very similar build: L28 flat tops with E31 that was shaved, around 11:1 compression, 490/.280 cam, 44s with 37 chokes, header and 2.5", MSD 6AL and ZX distributor, light flywheel, etc. Very similar sounding build. I did a lot of work done in the chamber to get rid of any hotspots, ground off extra spark plug hole threads, had all sharp edges removed, unshrouded valves, cc'd chambers, etc. As much work as I could do to it myself in the garage, basically. The head already had hardened seats installed and had a really nicely done blending of the bowls done by a local machinist. It made pretty good power but I always felt like for a really hot street motor I wanted something more in the .500/300 range. BRAAP was selling a cam that was something like .540/300 or something. That was the one that I had pretty much settled on before I decided on swapping in a V8 instead. It was still streetable but suppsedly made enough of a difference up top that BRAAP was endorsing it, and I trust his judgment. So would a bigger cam get more power at those RPM? He now gets ~220 @6500, with a bigger cam would he get more at that RPM? Or less at 6500 but more at say 7500 RPM? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 30, 2017 Share Posted June 30, 2017 You'd have to do it and test it to know for sure. My hunch is that the cam he has is leaving some hp on the table, just as my cam was, and I'd guess that he'd have more area under the curve. Quote Link to comment Share on other sites More sharing options...
Chickenman Posted June 30, 2017 Share Posted June 30, 2017 Contacted the dyno store today, they where out all weekend supporting rallycross competition,so hopefully on Monday I will have the figures. Regarding the 3500 dip, should I try to change the w low speed jet to 45F8 instead. Regarding the lean on top maybe go down one size in air corrector? Richness in AFR is above the point where idle jet ( 50F8 ) should have any effect. I would try a 145 main. to lean out the bottom, and then a 175 or 170 Main to richen the Top end a bit. Getting into twiddly stuff now. Quote Link to comment Share on other sites More sharing options...
Leon Posted July 2, 2017 Share Posted July 2, 2017 The AFR dip is due to the emulsion tube. You can work around it by fiddling with other jets but it will remain. Keith's e-tubes are the better solution but if you're in a hurry, try an F7 or F16. Set floats using Keith's method to 25mm below the jet stack table. Quote Link to comment Share on other sites More sharing options...
Ssaga Posted July 2, 2017 Author Share Posted July 2, 2017 Does seems like a common weber dip then, anyone here that run with Keith's jetting? Quote Link to comment Share on other sites More sharing options...
Ssaga Posted July 2, 2017 Author Share Posted July 2, 2017 This dyno curve is quite typical. Transition idle jet to main jet. You can change this a lot with keith franks hypos(idle) and obert e-tubes(main) or the new bb tubes(main). Pulls like a injected engine afterwords. Are you running any of Keith's jets? Quote Link to comment Share on other sites More sharing options...
munters Posted July 2, 2017 Share Posted July 2, 2017 Yes, I run them. The first big improovement are the Hypojets (Idlejet replacement). This is a really nice of idle driving change. The obert Tubes are far better main jets and do not have a lean top as any Weber main jets. (I was able to optain a 12.5:1 at 7500, my high shifting point.) With this 2 the car runs already nice. If you have an off idle (progression holes) quick changing AFR, you can use his third Jets, which are airleaks in the progression cirquit. They will give a nice steady acceleration in the transition between the Idle and main cirquit. (I could lower my consumptions by 2L/100km with those alone) Leon knows those Jets really well and he talked to keith in person if I remember correctly. Hope this helps Marcel Quote Link to comment Share on other sites More sharing options...
Leon Posted July 2, 2017 Share Posted July 2, 2017 Yup, I've been working with Keith for a few years. My previous L24 with DCOEs had an absolutely flat-line mixture at 12.5:1 using Keith's bubbling e-tubes. I'm sure I posted that chart in my old thread on the orange car. I'm waiting on Keith's newest development to put into my current Z. I've got F11 tubes and they have the same pronounced rich dip at 3000-4000RPM. Quote Link to comment Share on other sites More sharing options...
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