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Twin-Charged Bonneville: UPDATE 08-2011

Old 08-26-2011, 03:39 PM
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Default Twin-Charged Bonneville: UPDATE 08-2011

Hello to those of you who remember, this is my twin-charged 96 Bonneville SSEi. Not much has changed since 2010, new larger turbine housing (1.34a/r), revised wastegate dump tube integrated into a new 4" downpipe, oh, and forged pistons and L32 rods. The block is still std bore. Stock crank. ARP studs and Cometic h.g'*. Same heads and blower, intercooler system is still the same. Best previous was 380whp on 15psi.

I spent alot of time and effort to set the engine up to monitor EGTs. The 3800 with stock log manifolds is very imbalanced and right now I am running log-style headers up to the crossover pipe. What I thought was poor cylinder balance was alot worse than I thought! The cylinders had as much as 100deg EGT spread! I won't say which was which, but suffice to say, after adding or taking away fuel to/from 5 of the 6 cylinders (I will say that cyl #3 was the "reference"), I am now making 425whp on the same 15psi! It is all in the design of the headers... (this winter I will be building a set of short-tube equal-length headers for it.)

So all of this resulted in a best 12.50@115 at the Pontiac Nationals last month. I was running ice in the interooler tank, race gas, and slicks. On the last run, I ticked off a few turns of the boost controller running the boost bypass valve, saw 20psi on the boost gauge, and ran a 12.05, on the brakes at the top-end to keep from breaking out. (I did anyway, and lost the in the first round of eliminations) The mph was only 107 on that run... but the 12.05 would have easily been a high 11.80.

Here'* a link to the 12.50 run. I am taking the car to the Atlanta Dragway tonight to claim my 11-sec timeslip.


and this cool run, you can hear the turbo singing!


I know it will run 11'* because, I found out today, on 20psi combined boost and race gas with ice in the intercooler, the engine makes:

Attached Thumbnails Twin-Charged Bonneville: UPDATE 08-2011-jeffs485.jpg  
Old 08-26-2011, 03:44 PM
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Welcome back, and a good run. What cam, heads and rockers are you running again?
Old 08-26-2011, 03:47 PM
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Originally Posted by Danthurs
Welcome back, and a good run. What cam, heads and rockers are you running again?
stock cam (that'* why it runs out at 5800rpm), stock unported heads with oversize SI valves, HS 1.8 roller rockers. I added another vid above.
Old 08-26-2011, 03:50 PM
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Pick up a S1x cam, your power curve will be better then rockers alone. Put on some ported heads and run that cam with your 1.8:1 rockers and, well, your going to be moving a lot faster.
Old 08-26-2011, 03:52 PM
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Man, love the way that sounds going down the track.
Old 08-26-2011, 04:00 PM
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Originally Posted by Danthurs
Pick up a S1x cam, your power curve will be better then rockers alone. Put on some ported heads and run that cam with your 1.8:1 rockers and, well, your going to be moving a lot faster.
I think I'll keep it like it is. I like my peak HP under 6000. Keeps the rods where they should be! And right now, the forged powdered-metal rods are my weak link. If I had splurged on the Eagles, I would not care at all about it.
Old 08-26-2011, 04:01 PM
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Originally Posted by Danthurs
Man, love the way that sounds going down the track.
And that is thru the mufflers!
Old 08-26-2011, 04:03 PM
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How come your not running 1.9:1 rockers? Would give you a bit more flow.
Old 08-26-2011, 04:05 PM
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Very nice run. I'm with Dan on the sound, love it!
Old 08-26-2011, 04:05 PM
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the best part about it all: I drove the bonneville 650 miles from Atlanta to Norwalk, OH towing a 4x5 clamshell trailer loaded with two sets of tires, top tool box (200#), jack, stands, race box, huge fold-out canopy, and big *** cooler full of ice AND the trunk full with food, tent, two more coolers full of ice and food (one was 4ft wide!) AND the back seat full of bags, blankets and clothes up the back window. I got 18mpg towing, switched tires, and ran low 12'*! Then loaded all the sh*t up and drove home! HAHAHAHAHAHA!

The car weighed 4070# with me on scales. I bet I was over 5000# on the road!

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