10.0:1 compression adding a blower optional?

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jeepinocala1111
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10.0:1 compression adding a blower optional?

Postby jeepinocala1111 » Sat Mar 11, 2017 12:14 pm

Never ran a blower on an air boat but considering a Dyers 671 or 871 with about 4 lbs of boost. My engine is 10.0:1 compression has anyone done or is doing this? Results? Or shoul;d I just wait and build another engine for it later?
Last edited by jeepinocala1111 on Mon Mar 13, 2017 6:07 pm, edited 1 time in total.

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Re: 10.0:1 compression adding a blower optional?

Postby PAINKILLER » Sat Mar 11, 2017 9:26 pm

If I wanted a blower id call a company called The Blower Shop
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Re: 10.0:1 compression adding a blower optional?

Postby SWAMPHUNTER45 » Sun Mar 12, 2017 8:37 am

Jeep how did the 10:1 ratio get calculated?

The reason why I ask is many times a projected or advertised compression can be .5 / half a point below which in this case would benefit your interest in forced induction.

We have seen this process actually go both ways however.

An older block that had been decked or heads cut can see a .25 / quarter point gain.

Heads that have had extensive bowl work where the valve area is relieved can lower the ratio almost .25 / quarter point.

I had spent some time around a private shop in Tampa and the builder there liked 8.5 as it gave them the ability to run a wider pressure span. You may try stopping by Angels Airboats they are not to far from you and they actually ran a blower boat. I have not been by there in a while but they were helpful when I was there last.

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Re: 10.0:1 compression adding a blower optional?

Postby 406 JAMIE » Sun Mar 12, 2017 8:39 am

ur good with ur compression 10.1 but max comp would be 10.5 to 1 ,but its ur bottom end that needs all beefed up IMO.i would build a engine just for blower and i think a 671 should be enough.we slapped on a 871 blower on a 355 sbc old school and we didn't do anything to that 355 but slap 871 blower on it and i think we put a 850 double pumper dual feed holley.if u go on u tube and look up RANK HIGH PERFORMANCE and u will see a cpl videos we made at eau gallie mud park it was closed and we got permission to test and tune after they we're closed.and if u have any questions plz feel free to call 321-7271564 RANK HIGH PERFORMANCE DRIVELINE&MACHINING mon-fri 9-5/6pm.talk to rob or Michael.hope this help y all besafe plz :rebel:

Sorry i forgot the video with green 2.5 ton s-10 with 355ci sbc with 871 blower is the 1 im talking about and check out some of our other videos.
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Re: 10.0:1 compression adding a blower optional?

Postby jeepinocala1111 » Sun Mar 12, 2017 9:20 am

The engine is built right it has the right bottom end part and the compression of 10.0:1 was off the build sheet for the engine so if it was a bit lower that's a good thing but I am also only going 3 or 4 psi.


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Re: 10.0:1 compression adding a blower optional?

Postby 406 JAMIE » Sun Mar 12, 2017 9:36 am

instead of big blower 671 871 just go with one of those paxton superchargers belt driven.we did one on a dodge hemi in a big crewcab dodge truck sleeper and got almost 600hp at rear wheels.
And do u have fuel injection on ur LS?
And if so u will need laptop to be able to tune it to best tune possible for ur boat.and if ur looking to go with a lil more power maybe pull cam shaft out and have bullet camshafts grind u a special cam and a set of lifters to match and matbe have just exhaust ported.and porting ur intake ports would not help with airboat app if u we're all out racing and getting ur motor over 7/8 k rpm yes i would see porting ur intake runners but ur motor won't see that rpm.and u can change comp by changing head gasket thickness to lower ur comp to get u in safe zone for running a blower.hope this helps. :rebel:
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Re: 10.0:1 compression adding a blower optional?

Postby Deano » Sun Mar 12, 2017 9:50 am

My blower experience is limited, but from what I've seen and done, I would be inclined to purpose build another engine for the blower if that is an option. My assessment would be very similar to Swamphunter's friend in Tampa, in that lower compression will allow for more bang for the buck so to speak.

Not to say for a second that you couldn't blow what you have, but don't forget that smarter men that me have justifiably made the assessment that powering an airboat is almost like a perpetual dyno run and everything needs to be right for it to live long.

Compression maybe THE major consideration, but done right to live long, there are other considerations like bearing and piston clearances, ring end gaps and cam selection among other things that are more than passively relevant. It would require quite a stroke of luck, to already have an engine on hand that coincidentally exhibited all the preferable parameters for such an endeavor, imo.
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Re: 10.0:1 compression adding a blower optional?

Postby SWAMPHUNTER45 » Sun Mar 12, 2017 9:57 am

Making the assumption that your build sheet is accurate, a 4 pound boost put to a true 10.0 to 1 engine will yield a boosted compression ratio of 12.7 to 1 @ 40ft above sea level.

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Re: 10.0:1 compression adding a blower optional?

Postby jeepinocala1111 » Sun Mar 12, 2017 10:45 am

Deano wrote:My blower experience is limited, but from what I've seen and done, I would be inclined to purpose build another engine for the blower if that is an option. My assessment would be very similar to Swamphunter's friend in Tampa, in that lower compression will allow for more bang for the buck so to speak.

Not to say for a second that you couldn't blow what you have, but don't forget that smarter men that me have justifiably made the assessment that powering an airboat is almost like a perpetual dyno run and everything needs to be right for it to live long.

Compression maybe THE major consideration, but done right to live long, there are other considerations like bearing and piston clearances, ring end gaps and cam selection among other things that are more than passively relevant. It would require quite a stroke of luck, to already have an engine on hand that coincidentally exhibited all the preferable parameters for such an endeavor, imo.



Yes I am leaning on building another engine.

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Re: 10.0:1 compression adding a blower optional?

Postby 406 JAMIE » Sun Mar 12, 2017 10:48 am

whats wrong with ur engine u have in boat now?
I thought from ur treads u just built that LS?
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Re: 10.0:1 compression adding a blower optional?

Postby glades cat » Sun Mar 12, 2017 2:01 pm

It's more than just CR on blower engines. There is no coasting driving a prop. A lot of load, pressure and heat generated. Forged pistons, rings set lower in piston, chrome moly, plasma moly or stainless, high performance exh valves, boost referenced carb, matched cam, head studs instead of bolts, MLS head gaskets with smooth deck/head surfaces...to name a few things. If you want it to last when you put your foot down...and you will.
Post pics of your build, always interested in cool projects.
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Re: 10.0:1 compression adding a blower optional?

Postby digginfool » Mon Mar 13, 2017 8:13 am

For what it's worth, the LSA uses 9.5:1 pistons and the blower makes about 9 lbs boost in stock form. Of course, it has all kinds of sensors to safeguard against detonation as well as an air-to-water intercooler. When I ordered the parts for my build, I stayed with 9.5:1 Diamond Racing forged pistons, Callies forged rods, had ARP head and main studs installed as well as LS9 cam and head gaskets. I spoke to several people about going to higher compression and the consensus was that you will get more out of a blower motor with lower compression pistons than higher, both in reliability and overall increase in performance.
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Re: 10.0:1 compression adding a blower optional?

Postby jeepinocala1111 » Mon Mar 13, 2017 12:22 pm

406 JAMIE wrote:whats wrong with ur engine u have in boat now?
I thought from ur treads u just built that LS?


My engine is great I just like power and the more the better. I am dealing with two shops Rollins in Gainesville for parts and Dyers for the setup and system they are second to none. I think I can pull it off with just 3 lbs of boost.

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Re: 10.0:1 compression adding a blower optional?

Postby One Eyed Gator » Mon Mar 13, 2017 1:27 pm

If you have sq port heads just use the GM blower set-up. If you don't have the sq port heads get a set of LS3 heads and then blower. Can be done fairly reasonable.

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Re: 10.0:1 compression adding a blower optional?

Postby 406 JAMIE » Mon Mar 13, 2017 1:45 pm

jeepinocala1111 wrote:
406 JAMIE wrote:whats wrong with ur engine u have in boat now?
I thought from ur treads u just built that LS?


My engine is great I just like power and the more the better. I am dealing with two shops Rollins in Gainesville for parts and Dyers for the setup and system they are second to none. I think I can pull it off with just 3 lbs of boost.



yes sir there is always room for more HP&TRQ :thumbleft: :rebel:
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Re: 10.0:1 compression adding a blower optional?

Postby BGREEN427 » Mon Mar 13, 2017 3:26 pm

What will you gain with 3lbs of boost?

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Re: 10.0:1 compression adding a blower optional?

Postby jeepinocala1111 » Mon Mar 13, 2017 5:01 pm

3 psi is not bad. It can add a lot more than you would think. I would have to see a dyno to know for sure. I have seen it add 50hp at the rear wheels in a car taking away the driveline it would be more.

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Re: 10.0:1 compression adding a blower optional?

Postby One Eyed Gator » Tue Mar 14, 2017 7:51 am

A small amount of boost my not add so much HP but it sure does make a nice flat torque curve.


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