XS 550 Opinions

[Zach@n3]

Yea ha! I think his issue was that when he goes on his once a year trip pump premium isn't availiable at that location.

[biggator]

does anyone else find it hilarious that someone with a G23 with the XS550 even thinks about using Reg vs Premium?

What about those who don't trailer.. pretty sure they only sell mid-grade on the water at my lake.

[Quinner]

Oh fyi octane booster won't help your cause a bit

So what options do you have to boost the octane as/if necessary??

[Zach@n3]

Quinner, I was just stating that because most Octane boosters say they will boost it by 10 which isn't the same unit of measure as a octane point and it converts to 1 per 10 so most over the shelf stuff will take said gallons of 87 only to 88 octane. I read a few write ups on it years back.

My car likes to detonate on pump gas.... enough said haha.

Check this read. http://members.rennlist.com/951_race...omparison.html

[mcinmylo]

if you can afford a G23 with a 550 you shouldnt be worried about the gas.
if you dont have access to premium, either jerry it in, OR get a 450, remember the 450 works just fine. your not getting any less boat.

I wouldnt play around with octane boosters with that engine, the ratios are very specific and wouldnt wanna risk anything with that kind of price tag

[migs]

What about those who don't trailer.. pretty sure they only sell mid-grade on the water at my lake.

I would purchase a bunch of gas cans so I can buy my premium gas and bring it to the lake with me.

[jsta281]

A couple of things: First, I have no specific data or experience with marine applications. However, I am very familiar with positive displacement type super chargers, and somewhat familiar with the the Cadillac version of this motor. Here are a couple of comments on what has previously been posted. 1) a super charged engine not being as effected by altitude is not correct. It is not correct because the density of the air coming in still decreases the over all cylinder pressure as compared to what it would be at a lower elevation. The exception to this rule would be a supercharger with a blow off valve or similarly a turbo charger with a BOV, that is because the amount of air being pressurized and introduced into the intake can be manipulated or you can "turn up the boost" to compensate for the elevation. A belt driven PD motor has no BOV so it will still make less power at altitude. 2) Engines at altitude require less octane because the cylinder pressure will be less. That is not a suggestion/recommendation to run less octane, but if 91 is required at sea level it is almost a certainty that 89 octane would be sufficient at 5500 ft. However, if octane is a concern there are excellent products for boosting octane and increasing knock prevention. Torco makes a product Torco Unleaded Accelerator that works. I have been running it in my PD blower mustang for 8 years. I have standard CATS and O2 sensors. I run 21 pounds of boost (making 656 hp out of my 281 cid) on my stock motor adding 32 oz of Torco to ten gallons of 91 fuel that makes my octane approx 97. 32 oz of this product into a tank of fuel would easily "cure" any issue with mid grade gas being run in a stock application. It certainly would be alot eaiser to hall around then tanks of premium fuel.

As for longevity obviously that is a unknown as far as empirical data with the engine being new. That said PD blowers have been around, even in factory or standard equipment applications, for a long time. My 91 Thunderbird super coupe had one and It had 180K on the clock when I sold it with no super charger issues. I am not as well versed in the GM platform motors as I am with the Ford, but routinely rubbing shoulders with GM guys with that run these LSA positive displacement motors leaves me with little concern regarding longevity. A PD motor on "low boost" (10 lbs or less) would not have me concerned whatsoever in terms of being hard on the long block, the only concern would be if being under load most of the time (read boost here) as compared to a car (which is rarely under boost unless under heavy load or acceleration) would cause the PD blower to require more frequent maintenance/rebuild as compared to a car. My guess would be it would not.

[MileHiGuy]

Jsta281, interesting information on the octane booster experience - thanks for sharing. I have talked with one of the engineers at PCM and they would not give me any blessing on using such a product relating that they have no specific data or testing to support an endorsement.

To those that mock the use of regular fuel have not done a Lake Powell houseboat vacation. It's not about saving a few cents per gallon it's about availability and possibly questionable quality. It's not uncommon to take the houseboat 40-50 miles away from the nearest marina and all you have to refuel the boat for the week is with the toy tank on the houseboat. Premium is not available at all marinas and relying on our request to the previous owners to refill the toy tank with premium has trouble written all over it.

Now back here at home (5500') the 550 is a must IMO. Our dealer sold one with a 450 and will NOT do it again unless the new buyer signs off. Looking at the PCM altitude chart it is easy to see why as the 450 at 5000' makes nearly 10% LESS power than a 409 at sea level.

Awesome boat but it takes some stones to maker her roll!

[jsta281]

Jsta281, interesting information on the octane booster experience - thanks for sharing. I have talked with one of the engineers at PCM and they would not give me any blessing on using such a product relating that they have no specific data or testing to support an endorsement.

To those that mock the use of regular fuel have not done a Lake Powell houseboat vacation. It's not about saving a few cents per gallon it's about availability and possibly questionable quality. It's not uncommon to take the houseboat 40-50 miles away from the nearest marina and all you have to refuel the boat for the week is with the toy tank on the houseboat. Premium is not available at all marinas and relying on our request to the previous owners to refill the toy tank with premium has trouble written all over it.

Now back here at home (5500') the 550 is a must IMO. Our dealer sold one with a 450 and will NOT do it again unless the new buyer signs off. Looking at the PCM altitude chart it is easy to see why as the 450 at 5000' makes nearly 10% LESS power than a 409 at sea level.

Awesome boat but it takes some stones to maker her roll!

I can understand your reservation for using octane booster with out PCM's blessing, I'm not sure I would do it on a new boat, just so PCM could not blame me for the problem even though I know for certain it works. Being as familiar with it as I am, I would not hesitate using it in my boat if I felt it was necessary. There has been endless amounts of testing and data collection for both gm and ford applications. Somebody on Modularfords.com spent the money having it tested with 91 or 93 octane fuel. If it did not work my Mustang motor would have blown up or "detonated" with the first WOT run on 91 octane.

However, on my boat motor (ZR409) because I am at 4200 ft I don't think 91 is even necessary. If my boat is tuned to be safe at sea level on 91 there is no way it would have detonation issues on 89 or even 87 at 4200 ft making almost 70 less hp.

Regardless, I think you are making the correct choice if your altitude is 5500 ft., just imagine what your density altitude is on a hot summer day. I have seen DA's in the neighborhood of 9000 ft. on hot summer days at our race track where the actual altitude is 4200 ft.

[Zach@n3]

Blow off valves are not used for "turning up boost". Waste gates are used to adjust boost pressure in turbocharged applications. A waste gate either allows exhaust gas to bypass the turbine housing or be routed through the turbine housing. When the gas is routed through the turbine housing it spins the turbo faster thus creating more boost. The waste gate is a multi position valve that will regulate boost from nothing to as much as the turbo is able to produce. The boost signal to the waste gate canister can be manipulated in by a "boost controller" fooling the canister into thinking the turbo is making less pressure than it actually is. These usually hold boost pressure to zero visible boost untill the preset boost pressure is reached. It seeing no boost at all usually results in less turbo lag via quicker spool up from a completely closed waste gate. This can also cause the system to over shoot set boost levels or "spike".

Superchargers do not work like that. They have a belt drive with a given maximum boost via the gear reduction of the blower drive and the ratio of the belt pulley to crank pulley. A blow off valve is only necessary on centrifugal supercharger set ups running large ammounts of boost. On a roots style supercharger the throttle body or carburetors come before the blower. On a centrifugal set up or a turbocharged application the throttle body or carbs come after the boost producer. The blow off valve in these applications is a device that operates off of a vacuum signal from the intake manifold but also most aftermarket valves have an adjustable spring to make the valve capable of holding in more boost pressure from application to application. This will not allow the system to make more boost unless the BOV actually is the weak point. When this valve senses vacuum when you close the throttle plates the valve opens preventing back up of boost pressure and preventing damage to the supercharger or turbocharger. So if you want a blower to compensate for high elevation in any case you would have to use a smaller diameter pulley to produce more boost from said system.


Get that 550! I would be interested to see how my car reacted to torco because it does not like pump gas whatsoever especially as the temperature goes above 75 degrees. How much did you say torco ran a bottle?

[jsta281]

Waste gate/boost controller is what I meant not BOV so this is all correct. Thanks for the correction. I'm not a turbo guy so I sometimes get those terms mixed. The point, as you indicated, is PD blowers and most centrifugal blowers don't use a waste gate or boost controller and thus don't "create their own atmosphere" as some like to say when referring to a turbo which is not true either but waste gates/boost controllers do provide some means to overcome the effects of altitude where a belt driven PD blower does not.

[jsta281]

You can buy Torco by the 32 oz can or 5 gal pail the 5 gal pail is MUCH cheaper. A 5 gal pail shipped is $250 if interested check here

http://www.jbsblownc5.net/

I use "a lot" because I need to take 91 oct pump to 96+. Obviously it takes a lot less to only get a few more octane points.

One other thing: I think the charts you will see regarding mix ratios from Torco Are overstated to some extent. I do not follow their ratio charts. You can find a lot of data on modularfords.com forums.

This is what I go by
http://www.modularfords.com/f107/tor...le-tech-94528/

[Zach@n3]

Awesome, didn't want to step on your toes just clarify. I used to play with lots of turbo cars . Maybe I'll have another some day. I bet the stang is fun.... as in breaking the tires loose at 70mph fun!!!

I think the majority of the reason my car detonates is distributor over advance north of 4000 rpms. I need to get it recurved so it's all in around 2000. It isn't as extreme as your mustang. Judging by the numbers and mph it turns it's right around 390-400 at the crank via a very mild 360 build. Math wise CR should work out to be in the 10.5-11 range. High with Iron heads. :/.

[jsta281]

I don't mean to hijack the OP thread but it sounds like he has made his decision .

The mustang is very fast and fun (I ran 10.70 at 131 mph with a DA of 4300 ft. Last spring. However I have nothing but "boat on the brain" as my family refers to my new obsession.

As for your set up it does seem you could cure your issue with a little less timing up top, but if an extra bit of octane lets you run more timing that is fun too. It always seems to come down to a "cost benefit analysis"

[Zach@n3]

You can go as fast as your wallet haha. I believe either this winter or spring I will be tearing it down for a freshen and add more power if money permits. She's getting a bit tired. Shooting for the 450-470hp range I think. Roller and ported heads are in it's future. 13.19 at 104.00 is it's best. DR's and 3820 race weight. 1.87 60ft. 2600 converter it needs a 3200. I want consistant mid high 12's. Trans is getting a bit sluggish too.

I'm terrible at thred hijack. Thats enough! ha

550 here he comes!