Local shop wants $10K to upgrade to forged pistons, so turning up the boost isn't an option. Would heads on my 6.5lb cast setup result in any significant HP improvement? I also have full exhaust. Currently running 575RWHP. Would like to get it up around 650 or so.
No way just the pistons would be 10k. Maybe 2k-3k for the pistons. Unless they wanted to do rods while in there which makes sense, but you are still FAR from spending 10k. Tell the owner to find another sap to throw his money in the trash.
With the heads you would likely be over the "threshold" of the stock bottom end.
--wes
I respectfully disagree here on the "threshold", there is a lot of folks running that type of HP on a stock bottom end. A great set of heads might bring in an additonal 75 HP RWHP and that is all with that combo.
$10K for pistons is CRAZY! You can pull that engine easy actually, and anyhow I can see $5K installed or even $6K, but not $10K as the postons are only about $1.5K if memory serves me right.
I respectfully disagree here on the "threshold", there is a lot of folks running that type of HP on a stock bottom end. A great set of heads might bring in an additonal 75 HP RWHP and that is all with that combo.
$10K for pistons is CRAZY! You can pull that engine easy actually, and anyhow I can see $5K installed or even $6K, but not $10K as the postons are only about $1.5K if memory serves me right.
What do you believe to be the "threshold" of the stock cast bottom end? Everything I've ever heard/read says it's ~650rwhp. Yes, there will be a few that have a little more and they're fine, on the other hand there are folks with less that had their motors let go.
Keep in mind he is also SC'd. Some bad gas, a little detonation and boom when running on the edge like that.
What do you believe to be the "threshold" of the stock cast bottom end? Everything I've ever heard/read says it's ~650rwhp. Yes, there will be a few that have a little more and they're fine, on the other hand there are folks with less that had their motors let go.
Keep in mind he is also SC'd. Some bad gas, a little detonation and boom when running on the edge like that.
--wes
An engine is an air pump, not to sound condescending, and heads increase air flow, with a lower drag coefficient. It does not increase pressure all cc's of the chambers being equal, and should have no effect on the pistons. it will however have an effect on the crank, bearings, rods and the like, but again that 75 HP is nothing on those parts at his existing RWHP. You certainly can't hit 1,000 RWHP on a stock bottom end safely, and cast pistons do not like more than 6.5 boost, even that is close in my opinion, but the heads will only make the pump work a bit faster, make more power, but not work the pistons per se and anyhow I think without increasing pressure on the pistons, he can run 750ish RWHP safely with his bottom end as long as cyl. pressure does not increase. This is of course assuming he has adequate mixtures and the like and doesn't run lean, et cetera. personally, I would have only ran 5 PSI or changed pistons as I did. Just my $.02 but I was a business major, maybe some geeky engineer can chime in and kick my tail-lol. Gary
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Now that the prices of virtually everything are going up and up and now that thousands of people are losing their jobs everyday as the US goverment still hands out 10,000+ checks to those people just getting off the boat, I think I will take a boat ride and get in line, I sure could use the money to pay for the gas in my Viper and GTO!
Thanks for the feedback guys. I agree that $10K (they ballparked $9K-$10K) is damn high as it was just for pistons and full floating wrist pins on the stock rods. It's through a Dodge dealer, but there aren't a lot of known options around here without taking the risk of a bad build.
I have thought about tackling the piston swap myself with the block in the car, but with 33K on the clock the block may need some attention.
We have a fairly well respected local shop with Viper head porting experience which has some very attractive pricing on their website that got me thinking about just a head upgrade, though I know I would need a cam to get the most out of it.
I have had my Roe setup for 2 1/2 years and do all my own tuning to keep the setup running safe with my cast pistons. I also run Torco when I know I am going to be hammering on it to boost my octane since we are limited to 92 in these parts. Planning on spending maybe $5K on the motor this winter. Looking for the best bang for the buck at this point, but not looking to build a ticking time bomb either. If I did the work myself, I could do the heads, RRs and perhaps a cam if I was willing to tackle it for about $5K. If I thought the block would be OK, I could do a piston swap and pulley upgrade instead for around the same amount if I did the work myself. I have built engines, but that was a long time ago, so not 100% confident in tackling this level of work myself.
I would do RR, cam, bigger smooth tubes and TB's and maybe port the heads up and forget the forged piston upgrade. I have built about 6 engines in my life and never had a problem doing it, but this is only a little more power to do all that work by adding boost. The Viper was intimitating to work on for me when I got it, as I was like"it is a Viper-a different car", but I have come to appreciate that it is a great car, yet VERY easy to work on! I would do my motor myself in a heartbeat, but in your case, the 33K makes the motor still a baby and I would just run it with a few extra mods for extra HP and spend the time and money on the wife or GF :-)
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