Roman Posted October 16, 2023 Share Posted October 16, 2023 If you advance the ignition timing and the engine wants to make more power, but it cant because it knocks - then higher octane fuel will help your motor make more power, by allowing more ignition timing without knock. If you advance the ignition timing and the engine makes same or less power, with no knock. Then a higher octane fuel wont do anything. If you just switched fuel to something different with no other changes, it's unlikely you'll make any more power. Unless you're using partially oxygenated fuels (like E85) or nitromethane or whatever. hah. I'm fairly sure that back in the day, when MSNZ banned avgas for racing (or something similar, paraphrasing horribly probably) Everyone had a big sook about it, but then retuned their cars for 98 octane and found they made the same or more power anyway. 2 1 Quote Link to comment Share on other sites More sharing options...
Yowzer Posted October 16, 2023 Share Posted October 16, 2023 I've heard rumours that avgas makes 2Ts nang out hard. Need skids for proof of course Quote Link to comment Share on other sites More sharing options...
Alfashark Posted October 16, 2023 Share Posted October 16, 2023 6 hours ago, piazzanoob said: Ah right thanks Seen that avgas in rich form can get 130+ octane rating but nut sure if that is true or not 100LL is 100 octane... That's all folks. Quote Link to comment Share on other sites More sharing options...
piazzanoob Posted October 16, 2023 Share Posted October 16, 2023 6 hours ago, Alfashark said: 100LL is 100 octane... That's all folks. 1 Quote Link to comment Share on other sites More sharing options...
Alfashark Posted October 16, 2023 Share Posted October 16, 2023 You won't get it rich enough to see 130 without shitting the bed first, so 100 it is. Quote Link to comment Share on other sites More sharing options...
kpr Posted October 17, 2023 Share Posted October 17, 2023 Back in the day.On an octane limited turbo 1500cc 95 was good for about 15psi boost. 98 20psi. Half avgas half 98 was good for 24psi. Around the 30kw mark for each jump. Pretty sure it was the full lead stuff not 100ll Quote Link to comment Share on other sites More sharing options...
Dudley Posted October 17, 2023 Share Posted October 17, 2023 3 minutes ago, kpr said: Back in the day.On an octane limited turbo 1500cc 95 was good for about 15psi boost. 98 20psi. Half avgas half 98 was good for 24psi. Around the 30kw mark for each jump. Pretty sure it was the full lead stuff not 100ll Incorrect 1 Quote Link to comment Share on other sites More sharing options...
h4nd Posted October 17, 2023 Share Posted October 17, 2023 Pertol Barrie dispute incoming: FLAME WAR Quote Link to comment Share on other sites More sharing options...
h4nd Posted October 17, 2023 Share Posted October 17, 2023 Unexpected customer visit ate 2h, so only just getting to lunch: it's not so much that computers suck (and yes, yes they do). It's how much other peoples computers suuuuuuuck! 1 Quote Link to comment Share on other sites More sharing options...
h4nd Posted October 17, 2023 Share Posted October 17, 2023 59 minutes ago, Alfashark said: You won't get it rich enough to see 130 without shitting the bed first, so 100 it is. I think you'd be astounded how rich the Dai runs, for part of it's operating cycle, anyways Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted October 17, 2023 Author Share Posted October 17, 2023 Vacuum source question time. The Honda tb I'm using has its map sensor fitted here... Which takes its vac signal from the engine side of the throttle disc... This is fine. I'm happy with that. I'll make a vac line fitting to fit where the Honda sensor bolts on and run my vac tube to the ecus built in sensor. My question is this.. Would it be fine to add a tee to the vac tube for my fuel pressure regulator. My gut feeling Is that it's fine. Vacuum is vacuum and they'll both get exactly the same signal. But thought I'd check. Quote Link to comment Share on other sites More sharing options...
ajg193 Posted October 17, 2023 Share Posted October 17, 2023 Yep. On my engine I have a 2 port thing on the plenum - one goes to MAP and the other goes to FPR. Seems to be a pretty common thing on Toyota 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted October 18, 2023 Share Posted October 18, 2023 I'd go a step further and not bother putting vac on the FPR at all. As there's no real point in reducing fuel pressure for NA setup. 1 Quote Link to comment Share on other sites More sharing options...
mjrstar Posted October 18, 2023 Share Posted October 18, 2023 Think of the reduced load on the fuel pump! 1 Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted October 18, 2023 Author Share Posted October 18, 2023 Ahhhhhh. I've never really thought if its needed or not? I figure there must be some sound reasoning as to why they are fitted to many N/A japanese cars? Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted October 18, 2023 Share Posted October 18, 2023 in the same way that boost lowers the pressure differential, vacuum would increase it. so unless your ECU can compensate for this, a referenced FPR would be required? Quote Link to comment Share on other sites More sharing options...
kpr Posted October 18, 2023 Share Posted October 18, 2023 If its map based tune, run vac to reg. if running itb's and tps tune (alpha n) that doesn't reference map, I would run a flat fuel pressure. 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted October 18, 2023 Share Posted October 18, 2023 1 hour ago, mjrstar said: Think of the reduced load on the fuel pump! But higher differential fuel pressure is better fuel economy Quote Link to comment Share on other sites More sharing options...
Roman Posted October 18, 2023 Share Posted October 18, 2023 5 minutes ago, kpr said: If its map based tune, run vac to reg. if running itb's and tps tune (alpha n) that doesn't reference map, I would run a flat fuel pressure. I'd have thought that whatever the load source, you'd just have slightly different VE numbers at low throttle with it disconnected? Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted October 18, 2023 Share Posted October 18, 2023 i just came back here to correct myself on that, yeah you would just tune around the change in flowrate with VE table. i guess its only important for boost pressure where you might actually stiffle the flow enough to run out of injector unless you ramp up the pressure to compensate. Quote Link to comment Share on other sites More sharing options...
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