Ok guys ive got a fully built gsr my heads got blox dual valve springs, blox high comp intak and exhaust valves (gives it 0.3 comp), blox titanium retainers, blox tuner series stage 3 cams skunk 2 adjustable cam gears, heads been ported and polished, arp head studs,bwt map sensor,cometic head gasket, hondata intake gasket, blox tuner series intake, 68mm blox theottle body, blox tps, blox fuel rail, rc 310cc injectors, walboro 255 guel pump, MSD distributor,MSD distributor cap,MSD plug wires, my bottom end bored 81.5mm, eagle crank, manley rods, supertech 12:5.1 pistons, acl race bearings, eagle main girdle,itr oil pump,itr water pump,itr crank pulley, block guard, windage tray, and it will be tuned on hodata s300!

 

Have you already purchased these parts or is this a wish list? It is a very detailed grocery list or parts, but you are missing the main ingredients, tuning hardware!

What are you using for engine management and who is tuning it?

In theory you could run 12.8:1 CR on pump 93. However, your tune will require so much timing adjustment, in order to avoid knock/detonation, that you will loose more power than it's worth.

 

Thats all the parts i already have, and im gonna run hondata s300 and jom at motervations in trussville is gnna be the one tuning it.

What do you prefer to do?

 

Nice to see you have a tuner, most people don't even think that far. Even though it is the most important part of a build. If I were in this position, I would ask Jom @ motervations what he thinks! He will be able to tell you what he can and can't do and what the results will be.

 

Do your self a favor & stay away from the MSD distributor.
OEM honda distributor, cap & rotor & plug wires would be the way to go for your application.

Concerning the compression ratio, I do not recommend anything much over 12.0:1 on an 81mm bore bseries that is going to be driven on 93 octane daily.

 

You know my old LSV you tuned at bluemoon had 12.2:1 with the piston/head combo and milling done to the head. I noticed in the eCtune cal that the timing values used were that of the default P30 from Crome too however it ran perfectly fine on what was mostly Sunoco 93 up till engine failure that was my fault from the timing belt skipping a few teeth one day.

Granted it was running the crappiest cams which were Gen1 B16's so power was low and the dynamic compression probably allowed that much more compression on 93 to do so, bore was also 81.25 if that makes any lee-way...

 

I have an MSD distributor waiting to finish my build. Can you please elaborate on why I should not use it? Thanks!

 

Yea I agree here its a level of diminishing returns. Last year I had an 81mm lsvtec with itr cams a bit over 12:1 and it waa only able to run like 26 degrees total up top before the detonation became visable on the plugs

 

Yeah I'd also like to understand however I was more interested in the Accel internal replacement coil and if this would be the same case



OEM replacement fit

 

OP, you have a 4 bar MAP on a NA motor?

 

Wait.....did I miss something? WTF LOL... sorry OP but what Adam pointed out reminded me of this....

 

John I agree on the comp ratio, just curious why have been people recommending high compression lately? I used the low comp for my build but theres this new bandwagon lately about high comp. You just lower you room for tuning around detonation for nominal gains if any right?

 

The main train of thought is that this day in age unlike 10-15 yrs ago when VAFC's and fuel pressure modifiers were used for fueling and ignition retard modules for ignition, during that era it was not wise to try running high static compression ratios with boost because of the crude tools and methods used to tune where as now a days, software with precise and affordable hardware (made available to almost anyone) can be employed to pin point areas in a tune for a setup to allow for higher static limits and boost safely.

I tend to agree with this however the margin of forgiveness is still narrower with higher compression and boost vs lower compression at comparable boost.

Really, what needs to be done is a tuning comparison between two similar boosted setups where one has a higher static compression at say 10.5:1 vs 9.5:1.....even better the same motor with just a piston swap although not practical to get done all during a back to back tuning session like a cam, intake, or header comparison so someone would almost need to build two identical motors just having the static comp the test factor here.

Even without boost I've read the opinions of others in the NA forum from years before who all seemed to favor the 11:1 to 11.5:1 range over 12:1+ compression for 220+ whp B series 1.8-2.0L setups because this allowed for more flexibility with regards to not only more ignition advance but also dynamic compression from today street/track cam profiles......

Still.....I'd really like to see dyno plots of setups out there to see which tradeoff offers the greatest power gain or in what range.

John,

would you happen to have any dyno plots to demo which method for power gains offers the best return on power? I know we've all looked through a page or 5 at Jeff Evans dyno plots but I'm sure you've tuned a comparable number of vehicles your self and I'm sure you have your own preference for which method offers the best power gains?

 

Thats what I figure. But are we comparing apples to apples? I know the difference between premium and regular fuel is about .07 octane or so. But with these numbers is the scale quite large in regards to the compression were changing? or is it very nominal change?
Also if it is not such a significant change or it is, is the risk worth the reward?

 

I second the MSD warning, they're very problematic and in some cases devastating. Accel coil FTW.
I also second the warning to avoid compression over 12:1 for a DD. It can easily be done, but you have to tune it pig rich to avoid detonating.
Terrible for fuel economy, not to mention all the carbon buildup if you're not running ethanol.