Not your average GM 847 thread... track / dyno results on stock bottom end?
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Joined: May 2002
Posts: 611
From: Chicago 'burbs
Not your average GM 847 thread... track / dyno results on stock bottom end?
I've run across several posts here with guys that are either running the GM847 with too little gear, not enough valvespring pressure, or not enough supporting bolt-ons.
I've got an XE 224/230 that puts down 366 rwhp with stage 2 heads, longtubes and boltons. I'm tempted to upgrade, and this is the biggest monster cam that I've looked at so far. However, I'm kind of concerned that we haven't seen any amazing numbers out of this cam. I don't think I've seen anyone running mid 11's or putting down 400+ rwhp with this cam without a 383.
I'd hate to switch over to this cam and find out that I only bumped up 10 or 15 rwhp with a loss in low-end power.
So have there been any new developments with stock bottom end cars running this cam, preferably with ported heads?
Thanks!
I've got an XE 224/230 that puts down 366 rwhp with stage 2 heads, longtubes and boltons. I'm tempted to upgrade, and this is the biggest monster cam that I've looked at so far. However, I'm kind of concerned that we haven't seen any amazing numbers out of this cam. I don't think I've seen anyone running mid 11's or putting down 400+ rwhp with this cam without a 383.
I'd hate to switch over to this cam and find out that I only bumped up 10 or 15 rwhp with a loss in low-end power.
So have there been any new developments with stock bottom end cars running this cam, preferably with ported heads?
Thanks!
Registered User
Joined: Mar 2004
Posts: 116
Re: Not your average GM 847 thread... track / dyno results on stock bottom end?
A buddy of mine put down 411whp with boltons, a GM847, and LE2 heads on a stock 130k mile bottom end. He had it dyno tuned by Jeff at CAM, before the dyno tune he was putting down 380whp at 6k, he put down 411whp@6k and experienced some valve float after that and that wouldnt let him rev the motor any higher.
Registered User
Joined: Dec 2001
Posts: 426
From: Slidell, LA
Re: Not your average GM 847 thread... track / dyno results on stock bottom end?
I have the Combination Motorsports TN-236XL cam which is very similar to the GM847. I have slightly more duration on the intake at 236/242 versus 234/242, *slightly* more lift at .555/.576 versus .539/.558 (on 1.5's), and the same 112 lobe sep I think. If I can get the last of the bugs worked out today and tomorrow I'll have track times on Friday.
My bottom end isn't totally stock, I'm running Speed Pro PowerForged pistons on stock crank and rods, but I'm running stock LT4 heads. So my compression is slightly higher than a stock LT4 but I flow less air than ported heads. I also have:
-CSR electric waterpump and Cloyes double roller timing set
-BBK 58mm TB
-SVO 30# injectors
-Hedman shorty headers
-Proform 1.6 rockers
-Comp 987 springs
I'm also running a T-56 with Spec Stage 3, Motive 4.11 gears, and Nitto's
I'll definitely have N/A times after this weekend, should have juiced times next week or the week after. Might have some dyno numbers by the new year.
My bottom end isn't totally stock, I'm running Speed Pro PowerForged pistons on stock crank and rods, but I'm running stock LT4 heads. So my compression is slightly higher than a stock LT4 but I flow less air than ported heads. I also have:
-CSR electric waterpump and Cloyes double roller timing set
-BBK 58mm TB
-SVO 30# injectors
-Hedman shorty headers
-Proform 1.6 rockers
-Comp 987 springs
I'm also running a T-56 with Spec Stage 3, Motive 4.11 gears, and Nitto's
I'll definitely have N/A times after this weekend, should have juiced times next week or the week after. Might have some dyno numbers by the new year.
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