The actual raise in performance is a variable. While it’s easy to state a certain percentage, I normally say 3% since that’s about all one would get out of there particular build which would be a mello build, the return differences are build dependent and since there are so many variables to super similar builds, you can generalize but not nail down an exacting number.
As said earlier, there’s a lot more power in going from 7.8-1 to 8.8-1. Also, the reason many people push the octane limits in compression is to keep the cam from creating a lazy bottom end. Though it’s inky one part of a few that can help or hinder low end performance, it’s a big one with the wrong camshaft. Even more so crappy when your on the street where low end torque is needed most.
Sure! You can hide, mask and crutch a low compression engine with high rear gear, high stall converters, lightening up the car, but it still is crappy because there is no efficiency do to the low compression. It also shows up on the top end but not feel as bad.
Not breaking balls here ….
Your MP 360/380 is actually a good example since it is a 9.0-1 engine and the roller cam is 230/236 (I forget) on the intake. Not only low on compression but that single plane kills it for the street but yet, YET! Fellas have taken ilthat engine into the low 12’s.
All I hear from you on that engine is complaints.
Low compression, single plane, heavy car, low stall, very wrong gear set & tire size, the list goes on….
The drag racers I met with the create engine have everything opposite than what you have and they did like it a lot. Lightened car, high gears and stall, great suspension, slicks and skinnies, etc…
Thats how to make the low compression engine work but it’s not what most people want to do to there street, street/strip car.
Not gloating, but here’s a different take with higher compression.
My wife’s 360 is just under 11.5-1, runs a 224@050 Hyd roller cam, RPM intake, TF heads, runs on 93 octane, has a 2500 stall (yea it could use more… I know) 3.55’s turning 26X10 Mikey’s flame threads.
Stomp the gas and rubber burns and lays stripes easily for 50+ feet. Then hooks and books. Heck, a set of 4.10’s and I’ll lay rubber for a 100 plus feet for fun.