JeffR 51 Posted April 28, 2007 Due to the 'O-So-Common' oil starvation issues with these engines when pushed on track days, I recently rebuilt another 1.9L 16v engine this time looking for both reliabilty & a power upgrade. The spec now is as follows- B/V (36mm) head-3 angle seats, 41.5mm ports, Cams-Inlet 0.097" lift@TDC, 108 degrees centreline, Max lift-.448", Dur-274 crank degrees, (235 degrees@0.050"), Exhaust cam, dead standard- 0.32"@TDC, Max lift 0.36" 114 degrees centreline 83.5X88mm-1928cc, forged pistons-CR 11.2:1, 48mm throttle bodies, 40 cm (total) inlet tract length, 300cc/min injectors, MoTeC M4 eng management, PeterT baffled & deeper (early 205, 1.9 {Aust spec}) sump + spacer plate, XU10 windage tray, extended oil pump pick-up, uprated oil pump spring, chain & sprocket, wasted spark ign 4 X LS1 coils..... 98RON fuel. all which only gave an i underwhealming 146hp at the wheels (dyno operator allows for 25% drive train losses).....and the engine feels flat above 5000 rpm (in a 405-1100kg). Good torque curve-strong from 5K onwards (how do I attach the bloody Dyno figs)? I have a set of GTi16 extractors, modified with a 63mm outlet ready to fit, along with shortened inlet manifold length of 36 cm, but I think there is something fundamentally wrong in the basic spec.(I suspect the transition (taper) from 48-41.5mm using the oem inlet manifold isn't ideal either, but maybe not the only issue). Can someone offer advice please? Jeff Share this post Link to post Share on other sites
petert 560 Posted April 28, 2007 (edited) Hi Jeff, it's a shame you live so far away. I know the build of this one (it has my pistons) and Jeff has been given plenty of secrets by another well known Mi16 engine builder, Owen Wuillemin. It should go like stink and make at least 155hp at the wheels. There's lots of things we can't see however, and some things we can. First of all the things we can. Cam Timing: I think the exhaust cam should be advanced to around 0.060-0.065" @ TDC. If you don't have a spare vernier pulley, use a #3 pulley to at least get it to 0.045". Try moving the inlet to 106 degrees as well, even though common sense tells you that's advancing the cam. You've certainly got enough inlet timing to make more power. Do them one at a time. Ign. Timing: Could you please do a screen dump of the ignition table? Perhaps you are trying to run too much advance? Also, have you verified the basic setup? ie 10 deg. in the software = 10 deg. on the flywheel? Did you map the ignition on the dyno? Or just do fuel mapping from an estimated ignition map? The things we can't see: Cyl. Head: It should flow like gang busters, but do you have a flow chart you can post? Inlet Manifold: Mine does the same transition, 48-41 on a std. manifold, so that should be fine, but of course who knows what it flows like? Have you done a flow test with no valves, inlet on and inlet off? Also, 400mm is long. Try shortening down to 320-340mm overall. I've got your dyno charts somewhere. I'll post them for you. Have you also thought about going to another dyno, preferably DynoDynamics, and do a run in shoot out mode just to verify the dyno you're using? Edited April 28, 2007 by petert Share this post Link to post Share on other sites
petert 560 Posted April 28, 2007 I found your most recent dyno chart. It was a DynoDynamics! Torque curve is nice! Share this post Link to post Share on other sites
JeffR 51 Posted April 29, 2007 Thanks Peter for your detailed reply & for posting my results. I've got a spare vernier cam gear, so I'll re-time the exh & see what difference it makes. If I could find a (rarer) #4 pulley I'd have 0.060"@ tdc & could use the pin locking system again? Would advancing the inlet cam to 106 degrees be moving the power up the rev range? Not that I mind, just getting a clearer pic of its effect. You might be onto something regarding verifying the basic ign set-up. The ignition timing was mapped on the dyno, but I'm sure it wasn't verified this time. When he did a basic tune for me to run the engine in (to 5000rpm), it did ping until I changed fuel from Optimax to Mobil 8000. This has since been fixed on the full tune, but as you say timing may still be out. I'll organise the ign screen dump from him next week. Still haven't got the head flow data from previous owner, but he mentioned it flowed at about 320cfm (I think). I should have had it flowed again with & without my manifolds. It's probably not be wise to compare, but as we both have the same throttle bodies & inlet manifolds, did you see any significant drop in flow with it fitted? To shorten the manifold any further than 36cm (which I can achieve with shorter trumpets), I'd have to cut down another manifold & weld on the dcoe flanges. (Did I read somewhere you offer this service?), or pay the big $$$ for the Jenvey/Longman job. Plenty to think about and do... Jeff Share this post Link to post Share on other sites
petert 560 Posted April 29, 2007 I wrote that respone in the wee hours of the morning. Hand up if you can spot the mistake? The cam timing suggestion is wrong. Advancing the cam will REDUCE the lift at TDC, not increase it. Even so, I think it would be prudent to move the exhaust cam both ways (advance/retard) a few degrees. I wouldn't do any major changes until you've verified the ignition is correct. Share this post Link to post Share on other sites
