|12-15-2012 01:50 AM|
|Deathmunchy||I've been looking into this. I want to use the brodix ik 200's 64 chambers with probe -3.5cc domed pistons. I figured the -3.5 cc pistons would have a small enough dome to allow decent flame travel while still maximizing on power expression of the piston and CR. with a .04 quench you get about 11.3 cr vs flat tops at a 10.4. Cr's are off the top of my head from memory atm don't feel like finding the calc.|
|12-13-2012 11:36 AM|
|lg1969||I agree, that would be confusing. You change the heads or the pistons or increasing the cubic inch or decreasing the cubic inch will change the compression, too.|
|12-13-2012 08:58 AM|
|12-13-2012 06:24 AM|
GM only used domed pistons in the small block V8 engine in the 1965 327 CI, 375 HP Ram Jet FI engines. Those pistons increased the compression ratio one point, from 10.25:1 with flat top pistons to 11.25:1 with domed forged pistons. The 1965 375 HP, 327 CI engines were the only FI engines that had forged domed pistons and a forged crankshaft.
In the fall of 1965, I purchased a GM 327 CI, 375 HP (L84) short block and installed it in my 1959 Chevrolet Impala and raced in AHRA F1-E/HR at the Odessa (Texas) Raceway Park Fall Nationals. The short block came less camshaft, lifters and oil pump. I installed a GM 30-30 camshaft, GM edge orifice lifters and a 409 Chevy oil pump since a HV oil pump was not available for a SBC.
The Chevrolet dealership where I purchased the 327 FI short block was one of the few dealerships that received 1 of 69 COPO ZL1 Camaros in 1969. It was #6 COPO Camaro originally ordered by Fred Gibb Chevrolet in LaHarpe, IL. I was a friend of the dealership owner and he let me drive #6 COPO Camaro around town for an hour and to a coffee shop with a salesman. The #6 COPO Camaro was Cortez Silver and had an all aluminum ZL1 427 CI engine with a TH400 transmission. After a week of negotiations, the #6 COPO ZL1 Camaro was purchased off the showroom floor by Jim Hall from Odessa Texas and was prepared for the 1970 Trans-Am Series. After driving #6 COPO Camaro in the 1970 Trans Am Series, Hall scrapped the car. The 1970 Trans Am Series were Jim Hall's last racing events. I must be the only person that knows what happened to that car.
|12-12-2012 03:53 PM|
|hpete||The best way to clean pistons is in your ex-wifes dishwasher. I'm a really big d-cup fan when it comes to pistons (and other things).|
|12-12-2012 03:07 PM|
|lg1969||Chevy had 68, 69, 70 350 rated at 300HP they had 10.25: 1 comp using flattops. They used small chambered heads. It depend which heads you are using|
|12-12-2012 01:53 PM|
|12-12-2012 10:08 AM|
|techinspector1||I have nothing scientific to offer, just an opinion. I have never cared for domed pistons where another head could be used with flat-tops to get the same SCR. In my mind, I see the flat-top shooting the mixture straight across the chamber toward the spark plug, while the domed piston presents a slight restriction to the movement of gases over the dome. I also see the dome getting in the way of flame propogation after the plug fires. I see nothing wrong with using a dished piston to reach a target SCR, so long as the piston still has a generous squish pad opposite the chamber side, like the D-cup Keith Black design.|
|12-12-2012 09:09 AM|
dome pistons vs. flat top
|12-12-2012 08:08 AM|
I'm from old school, I like dome
|12-12-2012 07:59 AM|
kind of what mouse fink said. If you have a short stroke engine (283,289) you will need a dome to make compression,with a long stroke engine things change the other way,like if you build a 434.
you need to find the correct combination of heads and piston design to fit your application and displacement.
|12-12-2012 06:22 AM|
the dome pistons will have more compression. But yes flat tops are best for 350 engines with 64 cc heads.
4 valve reliefs are cheaper since they fit on both sides 2 need to be different on each side. so it cost more.
dome can hurt power if the head is not right for it. with 64 cc heads its not real easy to buy proper dome pistons that are not in the 12:1 range. BBC and hemis run domes with great success but requires a little know how.
|12-12-2012 06:00 AM|
dome pistons vs. flat top
|12-12-2012 05:24 AM|
Were can you find domed pistons that will produce 10:1 compression ratio?
Every domed piston I have seen produce at least 11:1 compression ratio compared to the same engine with a flat top piston.
|12-12-2012 02:15 AM|
|Sarrowood||Does it hurt to use a wire wheel on cleaning the top of a flat top piston?|
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