March 29, 2024, 01:02:04 AM

News:

For advertising inquiries or help with registration or other issues, you may contact us by email at help@harleytechtalk.com


48H and compression

Started by Big Dave, December 11, 2020, 11:41:11 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Big Dave

Question for the builders and Dyno Guys

I have a 09 FLHTCU 96 inch Bagger

Running 48 cams otherwise basic stk , with air cleaner and slip ons

CCC 192 front 194 rear , I think stock compression was advertised as 9.2-1

I have new 103 pistons from a wethead 2015 advertised as 10.1-1

I was just going to get my cylinders bored to match the pistons but wondered if 48s would handle a bump in Compression

Riding style is heavy touring 25-3500 rpm so low end torque is what I need

cams were great in a stk 96 , only doing this as i have to pull the heads for seals and breathers

Thanks

Dave

838

I ran a 95" at 10:1 with the 48. It was great. Needs an ace tune. 103" will rip 👍👍👍


Big Dave

I have looked at those my only concern was the wet heads had more compression versus the air cooled 103

Im doing it but was wondering what to expect - lived my life - no replacement for displacement

Dave

harpwrench

Wet heads higher compression is from smaller cc heads, same pistons either way

Big Dave


PoorUB

Use a .030" head gasket, not the stock .045". You will end up with 10.15 to 1 static compression.
I am an adult?? When did that happen, and how do I make it stop?!

Big Dave


rigidthumper

Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Big Dave

Powervision canned map then the Dyno

Dave

PBSTN

I don't know if they're needed. But you might install mcr's while the heads are off.
2010 flhr. 2003 FLHRSEI2. 1986 SUZUKI GS1150E.

Big Dave

Would be a bone head move not to I think , dont want to go  :oops:

Dave

rigidthumper

I think you'll really like that combo. If you can, measure/trim the cylinders to zero the deck height- helps with detonation.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

838

0 deck and .030" will put you at close to 205ccp. That'll be one snappy ride!!! Can the 48 be tuned at this compression?

To the OP... I notice every time there'sa new thread on the Andrews 48 it gets lots of (good) attention 👍.

838

It tuned real easy at 10:1. Which would be the .030" head gasket and no zero deck (assuming pistons down a few thousandths in the hole). But (as ridged said) the tighter quench helps detonation so might even do better at 10.15... but that's a question for an expert. I'm just a dude that ran the 48 successfully at 10:1 👍.

Big Dave

Real experience is worth a lot

Thanks

PoorUB

As much as guys like the 48, I ran them in a stock 103 and they felt pretty soft. A slight compression bump would help. Also, im my opinion Andrews compression recommendations are on the conservative side.

The .030" head gasket with raise cold cranking compression from 197 PSI to 204. If the guy doing the tuning can't tune it at 204 he probably can't tune it at 197 either.


Similar to Andrews 57's. They are supposed to be a drop in but they are kinda flat with stock compression, but haul real nice when you get close to 10.5 to 1 compression.
I am an adult?? When did that happen, and how do I make it stop?!

Big Dave

Thanks I like what your saying , waiting on the pistons in the mail then its time to start pulling parts  :baby:

Dave

sfmichael

depending on the miles of the bike I would recommend a valve job especially if you have access to a performance machine shop that can perform a good multi angle valve job

a performance valve job will add some very inexpensive horsepower and new valve stem seals are a plus
Colorado Springs, CO.

Adam76

Quote from: sfmichael on December 13, 2020, 08:52:51 PM
depending on the miles of the bike I would recommend a valve job especially if you have access to a performance machine shop that can perform a good multi angle valve job

a performance valve job will add some very inexpensive horsepower and new valve stem seals are a plus
Hey sfmichael, I'm still learning. Can you please explain what a 3- angle valve job actually
does to increase performers.. does it increase chamber volume?  How exactly does it help?
Thanks

Don D

Harleys stock valve job is 3 angles. Performance shops such as mine have seat angle combinations that enhance flow and are more concentric than a stock valve job, that is the goal.
Short story
When I was 21 working flat rate for a Mercedes dealer doing heavy line I told the boss I was doing a "competition valve job" on the MB heads. He looked and laughed, the valve job was 3 angles and the same as stock. Back then we used stones. that was a long time ago and some of the other terms being coined were "3/4 race cam"   :teeth:

Adam76

Quote from: HD Street Performance on February 13, 2021, 06:18:45 AM
Harleys stock valve job is 3 angles. Performance shops such as mine have seat angle combinations that enhance flow and are more concentric than a stock valve job, that is the goal.
Short story
When I was 21 working flat rate for a Mercedes dealer doing heavy line I told the boss I was doing a "competition valve job" on the MB heads. He looked and laughed, the valve job was 3 angles and the same as stock. Back then we used stones. that was a long time ago and some of the other terms being coined were "3/4 race cam"   :teeth:

OK thanks,  that's really good to know. So if a 3 amble job is not much better than stock....  what exactly is a competition valve job?  And if you could only do one thing to improve a set of heads, what would it be? Thanks

Don D

And if you could only do one thing to improve a set of heads, what would it be?

My point was about the advertising being attached to what is just good machine shop practices.

One thing OK, Our Blueprint Package includes a Serdi valve job that includes 5 seat angles intake and 3 exhaust plus a radius, two angles on the valves. A little port clean up and heads CCd, $275, if guides replaced add $100, plus shipping.

Adam76

Quote from: HD Street Performance on February 13, 2021, 06:38:31 AM
And if you could only do one thing to improve a set of heads, what would it be?

My point was about the advertising being attached to what is just good machine shop practices.

One thing OK, Our Blueprint Package includes a Serdi valve job that includes 5 seat angles intake and 3 exhaust plus a radius, two angles on the valves. A little port clean up and heads CCd, $275, if guides replaced add $100, plus shipping.
👍👍

Arseclown

Depending on where you are and ride (climate and fuel), at round 10.1-10.2:1 cr I'd consider the s&s570 cam which also comes with the ezy start feature.