lower compression build questions

[Stegs]

i have a lower compression build, i should have had more input with my engine builder, but life goes on


My thoughts is i want to boost the performance and hp

My initial thoughts was a hughes whiplast cam for lower compression motors. But then i was told it needs to have headers in order to get the most out of it? is that true?

My other thought is eddy e street 75cc heads, bump my compression almost 1 full point which should be a nice boost
then add a voodoo 268/276 cam,

later down the road do a rpm intake and headers...

im thinking the heads and voodoo cam will be my best bet for performance, but im curious on the hughes whiplash cam with stock manifolds?

 

[IQ52]

Any engine is going to run better with headers. I'm not a proponent of the Whiplash/Thumper cams but many people run them and like them. You don't need headers to use the Whiplash cam.

 

[Stegs]

Any engine is going to run better with headers. I'm not a proponent of the Whiplash/Thumper cams but many people run them and like them. You don't need headers to use the Whiplash cam.

they say there wont be enough vac to run my power drum brakes?
any truth to that?

 

[IQ52]

Hughes claims that you should have 9-11" of vacuum. I've found that most manufacture's claims are generally exaggerated. Do you want to pretend that you have a really hot engine or do you want your power brakes to work effectively?

 

[Stegs]

Hughes claims that you should have 9-11" of vacuum. I've found that most manufacture's claims are generally exaggerated. Do you want to pretend that you have a really hot engine or do you want your power brakes to work effectively?

i WANT brakes to work good, and i Want performance. Im leaning towards 75 cc heads and a new voodoo cam

 

[PurpleBeeper]

In my opinion, 9"-11" of vacuum at idle isn't enough to make your power brakes work... especially if that's really 7"-9" or something like that. I believe the biggest issue with idle vacuum & cams is the "overlap" and others on this site know more about this than I do. I think your idea about smaller combustion chamber heads and maybe some .020" thin steel head gaskets is a really good idea and the voodoo cam sounds like it's in the ballpark of a good one, but again, ask others on this site for cam recommendations.

 

[Yatzee]

i have a lower compression build, i should have had more input with my engine builder, but life goes on


My thoughts is i want to boost the performance and hp

My initial thoughts was a hughes whiplast cam for lower compression motors. But then i was told it needs to have headers in order to get the most out of it? is that true?

My other thought is eddy e street 75cc heads, bump my compression almost 1 full point which should be a nice boost
then add a voodoo 268/276 cam,

later down the road do a rpm intake and headers...

im thinking the heads and voodoo cam will be my best bet for performance, but im curious on the hughes whiplash cam with stock manifolds?

You didn't say what size engine you had but I guess it doesn't matter if you just want to make it a bit more stout by modifications. My experiences have led me to the following conclusions:
1-Performer heads are your best choice hands down unless you got a lot of cash
2-Adjustable roller rockers over hydraulic lifters are OK but roller lifters are best and determine cam type. I run hydralic roller lifters with regular rockers with no issues.
3-Voodoo cams are just freakin' amazing ( buy the cam/lifter combo in this brand)
4-Be very careful of head gasket brand and thickness. Good ones are not cheap. Checking valve to piston clearance is a must with higher performance cams.
5-Use top quality timing chains and gears and make sure to index the cam. You can't do this with run-of-the-mill timing sets.
6-Regardless of what anyone says, you need 18Hg of vacuum for any power brakes. You have two choices with low vacuum - Willwood manual or hydro boost. I like hydro boost.
It doesn't matter how many diaphrams or size of the diaphram under 18 ain't gonna cut it.
7-If in doubt, check online for a build that's already been done and note the specs for the build. This gives you "tried and proven" guidance and usually lists the parts used to do it.
We all like to think of ourselves as engine gurus but most often use mismatched parts. Quality and matched components allow crate engine manufacturers to put guarantees on their product and they know all to well that you're gonna boot the $hit out of their products.
8- You can't beat an RPM or Air Gap intake for performance at a value price.

 

[Yatzee]

You didn't say what size engine you had but I guess it doesn't matter if you just want to make it a bit more stout by modifications. My experiences have led me to the following conclusions:
1-Performer heads are your best choice hands down unless you got a lot of cash
2-Adjustable roller rockers over hydraulic lifters are OK but roller lifters are best and determine cam type. I run hydralic roller lifters with regular rockers with no issues.
3-Voodoo cams are just freakin' amazing ( buy the cam/lifter combo in this brand)
4-Be very careful of head gasket brand and thickness. Good ones are not cheap. Checking valve to piston clearance is a must with higher performance cams and thinner gaskets.
5-Use top quality timing chains and gears and make sure to index the cam. You can't do this with run-of-the-mill timing sets.
6-Regardless of what anyone says, you need 18Hg of vacuum for any power brakes. You have two choices with low vacuum - Wilwood manual or hydro boost. I like hydro boost.
It doesn't matter how many diaphrams or size of the diaphram under 18 ain't gonna cut it.
7-If in doubt, check online for a build that's already been done and note the specs for the build. This gives you "tried and proven" guidance and usually lists the parts used to do it.
We all like to think of ourselves as engine gurus but most often use mismatched parts. Quality and matched components allow crate engine manufacturers to put guarantees on their product and they know all to well that you're gonna boot the $hit out of their engines./QUOTE]

 

[ykf7b0]

I looked into the E-Streets 75cc (5090) heads myself before I knew that the RPM was offered in a 75 cc version as well. The RPM (60829) has ductile iron valve seats vs the powdered metal seats on the E-Streets. To me it is worth the extra money for the piece of mind of having good quality valve seats. Good Luck!

 

[Stegs]

I looked into the E-Streets 75cc (5090) heads myself before I knew that the RPM was offered in a 75 cc version as well. The RPM (60829) has ductile iron valve seats vs the powdered metal seats on the E-Streets. To me it is worth the extra money for the piece of mind of having good quality valve seats. Good Luck!

id spend the extra money, but double? wouldnt it be cheaper just to buy the e street heads and upgrade the valves?

Im leaning towards the e street heads, 75cc, that should bump my compression about 1 point. Right there is a nice boost in performance.

next on the list is a voodoo 268/276 cam, which will give me plenty of vac for my brakes.

Live with that until i can save up for a performer rpm intake and headers. But im thinking with new heads that flow better than 906s, bump my compression up and with a voodoo cam....that should be a very nice boost in performance compared to my lower compression build now

 

[ykf7b0]

Double? trends_auto has the assembled RPM 75 cc part# 60829 listed on e-bay for $804.34 each including expedited shipping. There are others also selling these heads assembled for around $1600 a pair.

 

[Stegs]

Double? trends_auto has the assembled RPM 75 cc part# 60829 listed on e-bay for $804.34 each including expedited shipping. There are others also selling these heads assembled for around $1600 a pair.

i didnt look on ebay. just thru summint
e street heads are 1400ish for the pair
performer rpm is 900 for 1 head...

 

[IQ52]

Im leaning towards the e street heads, 75cc, that should bump my compression about 1 point. Right there is a nice boost in performance.

Yeah we'd all like to think so, but in reality it is not so terrific. The horsepower increase from the heads will be from better air flow and not the compression. A calculator for horsepower increase from compression.........

http://www.wallaceracing.com/hp-cr-chg.php

And one for air flow.......use a depression of 28" and an air flow of 220 cfm (.500" lift) for the 906 and 260 cfm (.500" lift) for the E-Street (I don't care what Edelbrock lists for flow amounts)...................

http://www.wallaceracing.com/calcafhp.php

 

[rumblefish360]

Jim, you have flow OOTB Edelbrock heads before correct? Can you list what you have found?
E-Streets should be the same more Or Less.

 

[rumblefish360]

To the OP
The quote below.....

Any engine is going to run better with headers. I'm not a proponent of the Whiplash/Thumper cams but many people run them and like them. You don't need headers to use the Whiplash cam.

To help get your low compression engine running better, would require better air flow in and out.

While headers would be a good help and upgrade, depending on the level of performance sought you could do without headers. I would suggest there use, but, they are a pain to install and are not super durable like exhaust manifolds are.
Your call.

Also the same for the aluminum heads. Your stock cast iron can perform very well with just basic rebuild tech on them. Additionally, bowl porting them is still cheaper than new aluminum heads.
Your call.

Help us out. What is your goal?

 

[IQ52]

Jim, you have flow OOTB Edelbrock heads before correct? Can you list what you have found?
E-Streets should be the same more Or Less.

One of the best 906 heads and one of the best RPM heads I've tested

906 @ .400" lift 222 cfm........RPM @ .400" lift 254 cfm
906 @ .500" 234 cfm.............RPM @ .500" 276 cfm
906 @ .600" 237 cfm.............RPM @ .600" 287 cfm

 

[727]

I don't think you can run a head shim .020" head gasket with aluminum heads. You may want to get a set of 915's and use the head shim. It will give you close to 1/2 point compression vs the .040" felpro gasket.
Call Aero head to see if they have any 915"s available.

 

[rumblefish360]

Stegs, I have a low Comp '78/400 & thought about the 75cc head and a mild cam.
The only issue I have about it all is, how much duration & lift can the stock engine take with these heads?

 

[69 GTX]

I think a stock head will only take .510-.530 without machining, but verify that with someone. That's given you have the piston/valve clearance.

 

[Stegs]

My goal is more "streetable power"
I dont want a drag race motor, i want to improve upon my low compression build

What i have is a rebuilt 440. They used low compression pistons (30 over) on another forum, i listed all the parts they used in my build (straight from my reciept)

Everybody came back and figured i had roughly a 8.7:1 compression 440
My cam that i have now is actually a step down from the stock 440 cam
The car runs great, pulls pretty good from a rolling start, not exactly a barn burner from a stop light

My goal is to take what i have and improve upon it. I was told adding 75cc heads would flow more, add about 1 compression point (getting me around 9.5 or so)

I was also told, that the voodoo 268/276 would be a nice bump in performance from my cam now.
I wanted to keep the manifolds for now (manifolds should bolt on to the eddy heads)

Then ill add a rpm intake with a drop base filter.
A engine builder said, with those heads, cam(lifters etc) headers and intake i should be north of 450HP based on a former build he did (he tuned it to be north of 475ho with a bigger carb on his build)

well i dont know what i make now, but i can say if i mash the gas, sitting still at a red light, i will smoke the tires for about 20 feet and then the motor just runs out of steam.....then it will shift and pull pretty good
I just want more, im not looking for 500+ HP, just want to improve on what i have
I figured a bump in compression, better flowing heads, and a better cam should do the trick