Offshoreonly.com - Boost numbers and opinions needed

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Quote:

Originally Posted by BBYSTWY (Post 4651842)

Well if that doesn't convince me nothing will hahaha

I assume that holding this thing pinned for like miles at a time is a quick way to make a lot of scrap metal so with no chiller right now would say 1/4-1/2 mile WOT pulls after tuning be realistic??

no clue, no data to go on

you aren’t measuring cylinder pressures, IAT or anything relevant so this is all purely speculation and trial and error. Tribal knowledge and copying setups that worked is key since you probably can’t afford to do it multiple times or run powerful virtual models of your setup.

Quote:

Originally Posted by MILD THUNDER (Post 4651825)

3lbs more of boost will likely net you 75-100hp. Been there and done it on the dyno with a similar combo.

theres alot of factors that go into what amount of boost is safe. An 454 with locked timing, 177 blower, 9:1, single carb, warm coolant temps, small cam, will not tolerate the same boost as a 8:1, 8-71 equipped underdriven healthy cammed dual carb setup with a timing curve.

its all about managing cylinder pressures, and what octane is available. Your air intake temps shouldnt be very high, and with the right tune, 7-8psi should not be an issue at all.

i run 9psi on my 468s, 8:1, iron heads, superchillers, etc. Id run more, but im already spinning the engines to 6200-6300rpm with the props i have. With 10psi, id be probably in the 875-900hp range, and 6500rpm wot range. Pretty sure sooner or later im gonna push the crank out of the stock block.

DO IT, run 100 😎

Very true...not the kind of income to allow for rebuilding the motor over and over lol

How would one measure cylinder pressure and IAT?? I'm sure intake air I could get some kind of gauge but how would I measure pressures or is that not something that's measurable??

Quote:

Originally Posted by BBYSTWY (Post 4651847)

Its not something ever measured by normal people or aftermarket engine builders.

I gotcha...btw sorry if some of these questions are redundant to other threads of mine I just want to try and be as clear as possible fine tuning this guy as like I said I can't afford to keep rebuilding this guy lol

IMO, If you can't pin the sticks to the dash for a solid 2-3 minutes or longer, then something is not set up correctly.

I agree with that griff...just makes me leary to do it anyway for extended periods especially without a chiller at any boost level...Idk maybe I'm just scared of hurting the ole girl haha

I can tell ya chillers arent exactly a gigantic benefit on a setup like this. Dont get me wrong, they help, and anything you can do to lower charge temps is a bonus.

My intake temps with a chiller, vary with lake temp. On lake michigan, where the water is very cold, they run in the 100-110* range. Slightly hotter at loto late summer, in the 115-120* range.

icdedppl has 10-71s on his 548's, making about 7psi without intercoolers. His wot temps are in the 140-150* range if i recall.

what ive noticed, is the intake charge temp with the larger blowers, doesnt seem to increase a whole lot when you up the boost a couple lbs. I can only assume thats because they arent being spun more than 20% over, and the chemical intercooling from the gasoline is helping.

I have a prosport IAT gauge. Im monitoring both engines intake temps on the dash at all times. Glowshift now makes a nice digital gauge as well. I recommend getting one. Youll need to drill and tap the intake for the sensor though.

Icdedppl has 548's, 8.5:1 , dart iron heads. He runs about 7psi no intercoolers. He has egt , afr, iat, knock sensor monitor, etc. Hes been running that setup for a few seasons now, with quite a bit of wot time in a heavy old 38 cig. He just bought some intercoolers, will be interesting to see what his temps are after the install.

As Mild mentioned, I`ve been running 7.5lbs. Ive seen up to 8.3lbs on my data logs on my port motor @6300rpm.
I`m trying to push the Titanic thru the water so I`m usually already at 3.5 lbs at cruise(62mph) AFrs in the low 12`s, EGTs 1320ish. timing around 29* intake temp is always 140-150*
No powervalves. 82 jets in front, 102 in back .

5lbs is "safe" but kinda low if everything else is dialed in, meaning good timing map and AFR`s.
I have kinda the same set up as you.

My motors are currently having a growth spur , not sure where I`ll end up with boost. Going from 5.2% under to 2.1% over

https://cimg6.ibsrv.net/gimg/www.off...38b696548b.jpg

You could always just enjoy for a bit and add boost later .