750 Fuel Demon to 750 Street Demon

[BasicQ]

All but the 850cfm downleg have had anomalies, interesting setups and some well known factory quality issues.

The 850 annular had 87 primary jets and 89 secondary with a 6.5 power valve. Must have worked (at WOT most likely) for the previous owner but would have been insane rich at part throttle being annular. I have since reduced to 76 and 85 jets respectively.

The first 750 had the baseplate gasket problem and what’s rather large jets for 750cfm @78 primary and 86 secondary. Likely due to WOT tuning with .031” x3 emulsion each main well and .039 mab.

The second 750cfm had quality issues from the factory that are now corrected but otherwise factory specs.

This 825cfm has had.......65 jets installed in the primaries. Factory 76. Assume an attempt to fix part throttle cruise as these things have .037~.038” IFR, .070” iab and .039” mab and aforementioned emulsion for quite a rich transition and mains start. I had 75 on hand so I have installed them for now.

[img]https://i.ibb.co/9tgrQ0Z/0654317-C-0292-46-FF-AE0-A-167-B44-DAF6-C0.jpg[/img]


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[GtoGeoff]

Makes me glad I run Thermoquads! None of these issues, bolt them on & they run.

[BasicQ]

Makes me glad I run Thermoquads! None of these issues, bolt them on & they run.

Once the butchering issues and poor factory QC are fixed so do modular type H

[img]https://i.ibb.co/0rhyLHq/07-B5-B421-A111-40-D5-B5-F6-194-EC52-ADA9-E.jpg[/img]


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[BasicQ]

Off to Ballarat airport on Saturday. Ballarat Drag Racing club are doing a test & tune day. Not a fan of 1/8th mile but it’s better than nothing. Gives me a chance to do some real WOT tuning.

Will take 750, 850 downleg and 850 annular and try all three with their current calibration. 825 wont be ready in time. If Wot checks out ok and I can get more runs in I’ll fit some unaltered metering blocks and see how they go with them.


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[BasicQ]

Won’t be doing any AFR checking at the track this weekend. Have to do the old fashioned way. Got the new o2 sensor in the mail today and it looks like some scumbag has ripped Summit and put a used one back in the box and sent back for refund and I ended up with it.

One on the bottom is original with AEM wideband kit. I ordered through Summit the part number in the AEM manual that came with the kit and I got the top one.

[img]https://i.ibb.co/zmpRhPP/60928-A82-9048-470-B-8-A94-8-C1-AB2-AC626-B.jpg[/img]

[img]https://i.ibb.co/r2qx23k/C1-A9622-A-DA0-D-49-F7-8184-46-EC4-CAD530-D.jpg[/img]

Installed the one I received today for about 20 seconds. Enough to see it is faulty. It was already covered in carbon when it came out of the box.

Only told someone the other day I never had an issue with Summit.

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[46Crab]

Off to Ballarat airport on Saturday. Ballarat Drag Racing club are doing a test & tune day. Not a fan of 1/8th mile but it’s better than nothing. Gives me a chance to do some real WOT tuning.

Will take 750, 850 downleg and 850 annular and try all three with their current calibration. 825 wont be ready in time. If Wot checks out ok and I can get more runs in I’ll fit some unaltered metering blocks and see how they go with them.


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Will be interesting to see how the 750 goes compared to the 850 down leg and annular.

[BasicQ]

Will be interesting to see how the 750 goes compared to the 850 down leg and annular.

Picking up a removeable sleeve Race Demon on Sunday. that will give more cfm's to try.

it will come with the gold 1.500" venturi for 975cfm and silver 1.590" venturi for 1050cfm.

[BasicQ]

Went to Ballarat airport 1/8th mile today armed with three carbies and the Mickey Thompson’s. Turned out to be a fizzer as I could not get traction. Track was partially prepped but not sticky. Gave it 8 cracks but no consistency with traction. Because of that I only used the 850 annular already on there as comparisons would be half arsed unless full traction with each run.

The plan was to give each a run then adjust if necessary for 12.0 - 12.5:1 AFR WOT. The oxygen sensor crapped out last weekend, was able to get a replacement but as in the post above I was dudded with some mongrel putting his busted o2 sensor back in the box and sending back for a refund. So couldn’t adjust via AFR gauge so it was to be time slips and plugs. Didn’t get that far as there was too much skating around.

Best run with most traction was 7.59 sec @92.9 mp/h. And a 1.77 60’. There was a little peddling. Punched that into a few online 1/4 mile to 1/8th conversion calcs but doesn’t quite add up. Comes up with 11.92 on one, 12.03 @115 mp/h on another. Last time at Calder 60’ 1.75sec, 1/8th 7.63 sec, 1/4 et 11.83 @117.9 mp/h. That wasn’t a good clean run either as I was nosing over before changing gears. I since found out my rev limiter was telling lies, set the dials at 6500rpm it was activating at around 6000rpm. I upped the dials to 7200rpm and no such problem today.



Had to call it a day early as I developed a split in the sump that was leaking oil. I’ll fix that and then it’s back to waiting for Calder to open.


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[LXCHEV]

Damn, what a day out. Lack of traction is indeed the ultimate frustration.

On the topic of Calder - is there any news as to when they are likely to have street meets on again this year?

I'll be super keen to check out Heathcote once all the upgrades are complete too.

[BasicQ]

Damn, what a day out. Lack of traction is indeed the ultimate frustration.

On the topic of Calder - is there any news as to when they are likely to have street meets on again this year?

I'll be super keen to check out Heathcote once all the upgrades are complete too.

Was frustrating. Two runs hooked up reasonably good but not flat to the floor on green.

Not sure about Calder, on their website they say hope to have it running by late March

Heathcote is already up and running though. there was a TnT there on the weekend and an event this weekend. Only thing stopping me from going to Heathcote is the distance. However if I were to meet up with a group of guys for a TnT I might consider it

[HQ 368]

Heathcote meeting this week should be a good one, track is booked on Friday for a private test session.
Should be some decent hitters out there.
If the weather holds up, Sunday should be a good test and tune day with all the prep and quick cars from the previous 2 days.

[BasicQ]

Keep in mind .83 lambda is low 12's in afr, right where BP reckon BP98 makes best power.

[img]https://i.ibb.co/pLVwThq/7-A0685-EF-4-FD3-4786-9-AA9-D3-CEBDDDF121.png[/img]

(I’m thinking highest useful compression ratio is dynamic compression)


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[EH179]

[img]https://i.ibb.co/pLVwThq/7-A0685-EF-4-FD3-4786-9-AA9-D3-CEBDDDF121.png[/img]

(I’m thinking highest useful compression ratio is dynamic compression)


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I believe it is static comp...if you look at the limits for say, 100 racing fuel (11.5-13) or Methanol (15-17) - right where you need it.
If the above numbers are dynamic, what are the static comp numbers going to be?

[BasicQ]

I believe it is static comp...if you look at the limits for say, 100 racing fuel (11.5-13) or Methanol (15-17) - right where you need it.
If the above numbers are dynamic, what are the static comp numbers going to be?

Your logic makes sense and I think your right.

Curious what they mean by ‘useful’.

That chart is all I could find for stoichiometric and best power for BP Ultimate 98 as BP no longer readily share that info.

So boys and girls, if using a wideband with BP Ultimate 98 and displaying AFR scale it may be a little out. The sensor reads lambda and the gauge multiplies it by 14.7 by default.

If sender is sending .85 the gauge will read 12.5:1 but in reality it will be closer to 12.2:1.

No deal breaker but something to be aware of. If running e85 though the error will be greater.


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[BasicQ]

[img]https://i.ibb.co/JzbLw75/FC938-A34-493-B-4-E6-C-936-D-0-B05-B324-A2-AF.jpg[/img]


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