hp questions

[Matt Mc]

What is the approx. Prop HP of a 98 300Promax and what is it for a new 300XS?

How does the 300xs compare to the 300x?

[EuropeanAM]

Matt:

I'm not ignoring you.... gonna have to research your question.

If someone has information on 300X "actual output" in it's "factory configuration"... I'd be glad to hear it (don't think I've saved anything from back then).

What I can tell you, is that the 300XS will perform VERY nicely. Probably a better holeshot and "low end grunt" than the 300X. The 300X will likely have a "slight" edge against the 300XS at WOT... at least until it runs out of fuel.

I'm a real stickler for "economy AND power". For shootout purposes, I think every shootout ought to be done on the same rig... each with precisely the same amount of fuel. Run 'em full out until they quit.... so you're not JUST comparing "speed"....
Do this with the 300X and a 300XS.... the 300XS will be towing the 300X home.

[mikepags]

I have always wondered that also.............I run a 250xs and my team partenr runs a 300x on a tr22.........the hole shot is horrible but once that bows comes down and that engine gets above 3000 rpms you had better hold on to something.......what impresses me the most is the mid range acceleration......side by side my z21 ranger hops out of the hole faster but he can hit 70 before I hit 55....he can do 78-79 fully loaded at the end of the day in tourney

[Matt Mc]

any body ever figure out what auctual prop hp is on the three I mentioned above.

I am curious how much my old 98 300 promax put out.

Also am curious about how much the new 250 xs and 300xs puts out?

I am under the conclusion that a 250 is now putting out what my 300pmax would. So that makes me wonder what a new 300xs puts out.

[John Jackson]

What I have seen form stock pulls,
300X 321 HP, 250XS low 270's, 250XB mid 260's, 300 Pro max upper 280's.
I have not seen any 300XS pulls but have heard low 300's. The 300 Pro max has a higher rev limit and is easily modded to perform better. The hood scoop mod alone will put the 250XB just ahead of the 250XS.
These were corrected pulls, and atmospheric conditions and altitude will change these numbers. All these pulls are 4+ years ago, I have no current knowledge on anything beyond 2005.

[Matt Mc]

i had heard that the new 300 xs was putting down 300x numbers. You don't think that there is any truth to that?

[esdbass]

Matt: Kurt's 300X pulled I believe 326 HP on the Hydro Tec Dyno but call Wayne Worthy to confirm. My R & D Hydro Tec and Simon mods at about 324+ HP. I haven't run it yet but plan to swap out my stock powerhead in a few weeks

[Matt Mc]

and you started with a 250xs?

[esdbass]

Yes I got a lightly blown powerhead and Wayne & Eric made a R&D motor out of it and dyno'd it from it's stock format, though different mods to the final version at 324+ HP

It's going to be fun

[EuropeanAM]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by John Jackson &raquo;</TD></TR><TR><TD CLASS="quote">What I have seen form stock pulls,
300X 321 HP, 250XS low 270's, 250XB mid 260's, 300 Pro max upper 280's.
I have not seen any 300XS pulls but have heard low 300's. The 300 Pro max has a higher rev limit and is easily modded to perform better. The hood scoop mod alone will put the 250XB just ahead of the 250XS.
These were corrected pulls, and atmospheric conditions and altitude will change these numbers. All these pulls are 4+ years ago, I have no current knowledge on anything beyond 2005.</TD></TR></TABLE>

These are all fairly accurate PROPSHAFT HP OUTPUT numbers....

The current 250XS/ProXS are putting out about 268 at the propshaft (about 5hp lost dropping to 87 octane model... small loss for big $$$ savings in fuel).

Eli's (esdbass) numbers are CRANKSHAFT horsepower (not yet rated at the propshaft).

Eli- you need to get that thing mounted up and get some same-day comparison numbers!

[esdbass]

Don: Well you know who to call to help that "same day" comparison done, just tell Red it's BBC Merc 3L test so he'll have Jeff and himself at the ready for shop to the water and back tests Oh and make sure Red can send you the bill for BBC to cover

We'll make a go of it in a few weeks

BTW: Don do you have a Merc Dyno sheet showing the 5 HP drop from I assume the 05 250 XS to ones forward of that? It's interesting because Eric Simon says that the compression of the 05's and earlier to the newer ones are pretty much the same, it was other adjustments that made the motor be able to run 87*

[John Jackson]

Ely, I got the same from one of the design engineers on the XS program. Changing fuel curve, timing, fuel delivery timing and shape, etc., these opti's and totally different from any normal DI system.

[EuropeanAM]

I'm informed that the compression is essentially the same (and from the numbers I've seen in the shop, that would add up).

Powerheads for the '05 now superceed up to the "current production" powerhead.

As John mentioned, timing/fuel curve, etc. are where the majority of the changes took place.

[esdbass]

John: Yes I heard from Merc Tec it was largely in the fuel curve. I also note that the drivers are different and maybe Don would know but I haven't heard about as much coil issues on the older XS's either

[EuropeanAM]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by esdbass &raquo;</TD></TR><TR><TD CLASS="quote">John: Yes I heard from Merc Tec it was largely in the fuel curve. I also note that the drivers are different and maybe Don would know but I haven't heard about as much coil issues on the older XS's either </TD></TR></TABLE>

Yes, the older style ignition had externally mounted coil drivers. They were also "single-strike" coils (and the combination of these operated a little cooler).

The newer "multi-strike" coils were designed to improve idle quality, and also help to provide for a "cleaner burn" of fuel at some RPM ranges.