|01-09-2013 04:53 PM|
|Camaro R/S LT||
|01-09-2013 03:41 PM|
Personally I dont think that I would go after a 76cc combustion chamber head to make up what ever CR I was tring to achive. I would be affraid that it would be too large of an area to maintain a good "burn" or quench pad area. I would not go any larger than a set of 72cc heads. If you where to use a 72cc head and a flat top piston then you would end up with 10.2:1 compression which on a motor with alm heads is easily run off of pump gas, heck my 11.2:1 CR motor can and has run on pump gas.
Dont let a good quality dished piston fool you, they have D dished pistons now, they are not like the old O oval dished pistons that had horrible quench pads. the D dished pistons are shaped so that they keep the same style quench pad as a flat top. I had 18cc dished pistons and made just over 500hp on pump gas with them, these are the same ones that I have in my gargae that still look brand new.
|01-09-2013 03:33 PM|
|my87Z||Okay this thread is tripping me out, I see posts I made months ago, that are in the mix of posts that I have made today. They aren't even in order. Anyone else notice this. Then it gives a date back in November for the some of the posts that I have made today.|
|01-09-2013 03:24 PM|
I know all about this, at first I used a well built 700r4 with it's 3.06 first gear and a set of 4.10 gears which comes out to a drive ratio of 12.55, if you compair this to a th350 and it's 2.52 first gear it would be the same as running a 4.95-5.00 rear gear with a th350, then the 700r4 has a 1.63 second gear which is about the equivilent of running a th350 (1.52 2nd) with a 4.56 rear gear.
this was all in a high 11 sec car, I enjoyed the o/d if I was driving on the highway (which was rare) but I didnt enjoy trying to make it hook. My 60ft times were too inconsistant because I had the hardest time finding that happy medium on take off. Not to mention that 1st gear felt like a "granny" gear. I have since swaped out to a th350 and now have 4.56 rear gears.
|01-09-2013 03:05 PM|
|Camaro R/S LT|
|01-09-2013 01:18 PM|
|vinniekq2||afr dart edelbrock and almost all the others have 76 cc chamber heads,just ask them|
|01-09-2013 01:09 PM|
|Camaro R/S LT||So its been a while but I'm still searching...looking for some 190cc heads with 76cc combustion chamber bc i want to run flat top pistons...however I can only find 76cc combustion chambers on heads that are maybe 170cc or lower?? Do heads exist that are 190cc with 76cc comb. chamb.? and where are they?|
|11-18-2012 07:53 AM|
With newer flat tappet cams they already have aggressive ramp rates for the material and the design of the lobe to lifter geometry. Using a 1.6 rocker increases this ramp rate, meaning that it will cause the valve to open farther and then close in the same amount of time. This increases stress on the cam lobes and lifters. If you are just talking about using a roller rocker on a flat tappet set up, you can do it. In this case since you didn't spend a bunch of money on the rest of the valvetrain I don't see a big need to spend a bunch of money on the rockers.
As for the cam you are talking about, if the cam card says 2500-whatever, this is just a broad-generalized guesstimate made by the manufacturer. You also have to understand that these guesstimations are made based on an engine of 350 cubic inches. You are planning on a 383, those extra 33 cubes eat up some of the range on the cam (the larger the displacement, the more duration is needed to produce the same effect). So as a general rule of thumb you can take about 500rpm off the guesstimated ranges. If the cam card says 2500-6000 then it will be closer to 2000-5500.
I didn't look into the cam specs of the cam you are looking at but I have built and driven a good few 383s, and for different uses. What I have figured out with the experience is that street 383s like around 222-232 degrees of duration at .050 (keeping in mind 9.5:1CR, mild heads, dual plane intake)
|11-17-2012 10:02 PM|
|vinniekq2||put the same cam in 4 degrees early for a sooner response,or use 1 size smaller cam|
|11-17-2012 09:46 PM|
|Camaro R/S LT||
So 2 question:
What kind of difference is there between 1.5 roller rockers and flat-tappet?
I'm leaning towards Comp Cams XR288HR. One thing I don't like about this cam is that the RPM Range starts at 2500.
I want something closer to 1600-2000. Is there a better cam?
|11-17-2012 01:41 PM|
|my87Z||Those combos and their power numbers seem a little optimistic for the parts used but either of those set ups (15-17) should easily produce 430-460hp and be a real nice street motor with some fun strip time.|
|11-17-2012 10:57 AM|
|Camaro R/S LT||
|11-17-2012 07:14 AM|
if heads are already sourced then use what gives you the compression you need/want..
if heads are not already on hand and need to be bought..
flat top 99% of the time is the better choice.. and use the heads chamber size to get the compression you want... no always possable ..but mosttimes you're not reinventing the wheel.. and the parts needed are out there..
of cource I'm talking n/a, boosted is a totally different animal
|11-17-2012 12:27 AM|
|Camaro R/S LT||flat top or dished pistons: pros/cons?|
|11-15-2012 09:35 PM|
Check out this 383 Scat rotating assembly. This rotating assembly is used in a 2pc rear main seal block. It is external balanced and comes with a balancer and flexplate. Scat Engine Rotating Assemblies 1-90355BE - SummitRacing.com. This assembly is for using 64cc chambered heads for a compression ratio of 9.7. Here is a 383 Scat rotating assembly for a 2pc rear main seal block. It is also external balanced and comes with a balancer and flexplate. SB Chevy 383 Scat Rotating Assembly Kit, 3.750 Stroke 5.700 Rods 9.8:1 Hypereutectic Keith Black Dish Pistons - 383 Kits with 5.7' Rods - 9000 Series Kits - Small Block Chevy - Scat Rotating Assembly kits - Rotating Assemblies | CNC Motorsports | Car. This kit also uses 64cc chambered heads for 9.8 compression ratio. Since you are going to have a stick shift transmission I also looked at this 383 Scat rotating assembly. It has 6" rods and Keith Black Hypereutectic 18cc Dish Pistons. This is an internal balanced assembly by CNC Motorsports. The balancer and flexplate (which is not needed) does not come with an internal balanced kit. It also uses 64cc chambered heads for a 9.8 compression ratio. SB Chevy 383 Scat Rotating Assembly Kit, 3.750 Stroke 6.000 Rods 9.8:1 Hypereutectic Keith Black Dish Pistons - 383 Kits with 6.0' Rods - 9000 Series Kits - Small Block Chevy - Scat Rotating Assembly kits - Rotating Assemblies | CNC Motorsports | Car.
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