Fun Twin Turbo BBC Junker! - EDIT now 9.411

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NME308
Posts: 187
Joined: Thu Jun 20, 2013 10:40 pm

Fun Twin Turbo BBC Junker! - EDIT now 9.411

Post by NME308 »

https://www.youtube.com/watch?v=COsIIfw4JiI


Fun Fun Fun!!! :D 8-) :D

Meet my supercharged outlaws buddies who had hurt the big bad 7.36 second 190+mph 16/71 roots blown engine. I have crewed for them in 2013 after installing a data logger in their car. They were able to tune their combo from 7.84 @ 178mph at the start of the year down to 7.36 @ 196mph with the data logged information. This was all done with a GM 454 4-bolt truck block, regular JP forged pistons (not half inch thick blower spec crowns) and regular eagle rods. Everyone thought these guys were just cowboys who were trying to play with the big boys, but over the 2012 season they had crept down unknoticed to the 8.0 quarter mile region. With their dive into the 7's the experts all concluded they were extremely lucky and would grenade their junk sooner rather than later! The string of 7.3 second passes at the end of 2013 however gave them the fastest door car in the region. ;)

The old fella who owns the gear is a retired panel beater who simply CANNOT sit still! :lol: He wanted to race the last meeting of the 2014 season with something, ANYTHING, and the machine shop was taking their sweet time repairing the damaged head...

Enter a gm 454 crate motor with plenty of miles up, a pair of ancient mack truck turbos, my old 650cfm gasoline blow through carb from the celica, my old MSD6AL-2 programmable ignition and whatever else was available on the cheap!

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To say I was nervous leading up to the weekend would be an understatement!
The stress points?
My home built blow through 650cfm carb.
The relatively stock 454 crate motor (stamped rockers, standard valve springs etc etc).
10.5:1 compression with only hypo-utectic(?) pistons. A previous owner had lunched a piston so these had made their way in and the engine had to be run on about 10 degrees less than average timing to stop it pinging its head off on pump gasoline! :shock:
98 Octane pump petrol.
No wideband.
Nobody else thinking I had a chance of making it work!

An off the trailer run of 11.3 @ 119mph with about 5psi boost and WAY too much fuel with FAR too little timing gave me great optimism for cranking this hand grenade up!

Enter run two with less fuel and more timing which was beset with the engine losing power each time it hit the 5psi boost mark or thereabouts??? :confused: With the next two runs I tried eliminating one potential cause each time and still had the drama. For the 5th run we had only one more of the three potential causes left to try and only two runs left for the night... So I removed the silicon hoses from the front of the turbo's which although were large diameter and theoretically free flowing were in hindsite sucking closed as the engine tried to ingest lots of fresh air. Because I had hoped the waste gate springs would give 10psi and it turned out to be only 5psi we thrashed through the mini nightmare of putting dual springs into both gates and clamping them shut again.

I wish I had video'd run five because the thing appeared to be running full afterburner from a Mig25!!! The result was 10.99 @ 118mph and as soon as I realised the spark plugs and pistons had not been melted out of the engine entirely it hit me that I had not revised the timing map. Since the china direct 60mm waste gates were of unknown quality I had set the MSD6AL-2 ignition to dump 25 degrees timing after 10psi boost which would leave us about 3 degrees just as a secondary overboost protection! I crossed my fingers and toes and gave it back 13 degrees hoping not to turn the engine to shattered glass.

As you can see in the youtube video link at the very top of the post the driver did not sit on the 2-step limiter long enough to build any boost so the part where soot starts misting out the pipes is where the turbos are getting their act on. Somewhere in between 330ft and 1/8th mile the car attempted to eat the driver on the 5000rpm change to top gear (2 speed powerglide) so he aborted the run. The boys all being supercharged experienced only were trying to work out why this baby turbo motor with 400hp less than the supercharged combo had turned the car nasty. Once I explained that while we probably had only around 800hp there was most likely 1000ft/lbs torque they started to get the picture!

So my two greatest desires for the days racing had been achieved. Within six quarter mile runs we managed to get a half handy tune into the engine. More importantly however I had managed to show the supercharged boys that a turbo car can and will try to eat you at any point of the run - no soft linear power delivery when the boosting device isn't driven from the crank!

Cheers,
Jason
Last edited by NME308 on Sun Apr 26, 2015 7:04 am, edited 1 time in total.
BOBLOOK
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Re: Fun Twin Turbo BBC Junker!

Post by BOBLOOK »

Great story and expiriance Jason thanks for share se forward when the refresh the block and stay turbo :lol: :lol: :lol: :lol:
The day we learn to think
NME308
Posts: 187
Joined: Thu Jun 20, 2013 10:40 pm

Re: Fun Twin Turbo BBC Junker!

Post by NME308 »

UPDATE:

So yesterday was spent in the ongoing quest to permanently convert my supercharged outlaws buddy's to turbo power!

There was no pressure or anything - but - the guy in the other lane in the below video is a mate of theirs and there was a friendly wager on the run... Apparently if we lost I was going to be walking home! :eek: Backstory is that old mate handles the truth somewhat liberally and we were not at the last race meeting where he claimed to have run a '10'. He also seems to be able to convice himself of the veracity of his own truth stretches... Since we had only run a couple of low 11 second passes late last year he threw out the challenge. Our pass of 9.411 scorched his 13.8 and I enjoyed a comfortable ride home again! He did manage to get his rig down to 12.2 later in the evening...

My water meth strategy had been somewhat a point of controversy as when you demonstrate the 1.6 liters per minute flow through the nitrous plate the average response is to the effect that you cannot possibly be doing anything other than putting out the flames... It sure does look like a stupidly large volume when flow testing into a bucket! The previous race meetings gremlins had added weight to the suggestion that even less water meth than the already reduced (we had adjusted on the fly to 700cc's per minute) may be required. I stuck to my insistence that if they wanted to run a full quarter mile on 15psi boost with pump 98 octane fuel on a 10:1 compression otherwise bone stock 454 BBC WITHOUT running over the crankshaft then best to start back with the 1.6 liter restrictor. I made sure there was plenty of timing of course and as you can see from the video there was no black soot like last time. So in the end it turns out the venerable WW2 research papers still hold true (using lots of water meth sure isn't something I invented...)!!

They are starting to like this turbo thing just a little! ;)

https://www.youtube.com/watch?v=8QB7kQQf7tc

Cheers,
Jason
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