HPBCANADA.COM • View topic - Best lower for drag

I have taken the T valve out & run water directly out the heads,
Motor has always run this way. (other boat)

Idle (1800 rpms) I am only getting a lb of pressure.

WOT, trimmed correctly, Im getting 7-8 psi.
Trimming, I gain 2-3 lbs.

I ran with regular gas this summer & motor would hit 1200 degrees before 8000 rpm's.

I have always run Avgas (leaded fuel), which always helped on temp.
I ordered another 50 gallon drum & will be ready for testing, next spring.

I think I am sucking air, since I changed the water pump to 3/4.
I did not add cocking last time I changed the pump.

Same lower on my Awesomecat, 1/2 water pu. = 15-20 psi water pressure.

This is why I am looking for another lower.
Don't want to remove from one, change pumps & install on the other.
Big pain in me behind

Once I get a new lower, Avgas, then the set up will start.
Avgas in a 260 center horn works great!!

Author:	stv92 [ November 16th, 2012, 8:33 am ]
Post subject:	Best lower for drag
Going to run my STV modvp with 20" ridgeback & 260 motor. Need to replace the lower & since Im going to drag, what would be the best CLE,Sportmaster? Ran one of my 2 whole Cle this summer but did not get good water pressure with it. Gears 2:1 or 1:87 ? May not be the fastest, but need all the help I can get

Author:	Jeff Yammer [ November 19th, 2012, 10:45 am ]
Post subject:	Re: Best lower for drag
stv92 wrote: Going to run my STV modvp with 20" ridgeback & 260 motor. Need to replace the lower & since Im going to drag, what would be the best CLE,Sportmaster? Ran one of my 2 whole Cle this summer but did not get good water pressure with it. Gears 2:1 or 1:87 ? May not be the fastest, but need all the help I can get Not sure if you were too high or not but a 2 hole CLE shouldn't have water pressure problems. For drag racing generally you set the motor a bit lower or whatever works for you and your set-up. Seems like you have a few small issues to work out. All part of the fun

Author:	stv92 [ November 19th, 2012, 5:44 pm ]
Post subject:	Re: Best lower for drag
This STV is my new one and have not made many passes with it yet, My last one STV Drag, went bottoms up That one was set up perfect! Took the motor off the other one & put on this one, Same time changed the lower. The 2 whole cle is one of three off my Awesomecat. But the STV is a 3/4 water pick-up & the Awesomecat is 1/2 Everytime I have to change water pump, its a pain! But, Im thinking its losing pressure around the pump? Motor had great water pressure on my other STV (same mid & power head), Will be ready for next season STV92

Author:	AnthonySS [ November 19th, 2012, 8:09 pm ]
Post subject:	Re: Best lower for drag
STV92...how many pounds of WP are we talking and how is the Head Water Temp in relation to the WP you are getting....you don't need a lot of WP to keep the engine cool at speed...also make sure you have restrictor washers in the t-stat housings...to keep some water in the block... Also had another STVowner complain about Low WP and watched him do some passes...I said trim the engine out to level...and his WP came up...he was running too much neagtive trim which set the the water pickup higher than the bottom of the boat and was starving the engine for WP and it was running hot....just a thought to consider ...keep us posted

Author:	stv92 [ November 20th, 2012, 12:02 pm ]
Post subject:	Re: Best lower for drag
I have taken the T valve out & run water directly out the heads, Motor has always run this way. (other boat) Idle (1800 rpms) I am only getting a lb of pressure. WOT, trimmed correctly, Im getting 7-8 psi. Trimming, I gain 2-3 lbs. I ran with regular gas this summer & motor would hit 1200 degrees before 8000 rpm's. I have always run Avgas (leaded fuel), which always helped on temp. I ordered another 50 gallon drum & will be ready for testing, next spring. I think I am sucking air, since I changed the water pump to 3/4. I did not add cocking last time I changed the pump. Same lower on my Awesomecat, 1/2 water pu. = 15-20 psi water pressure. This is why I am looking for another lower. Don't want to remove from one, change pumps & install on the other. Big pain in me behind Once I get a new lower, Avgas, then the set up will start. Avgas in a 260 center horn works great!!

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Author:	Himagain [ November 20th, 2012, 3:36 pm ]
Post subject:	Re: Best lower for drag
stv92 wrote: I have taken the T valve out & run water directly out the heads, Motor has always run this way. (other boat) Idle (1800 rpms) I am only getting a lb of pressure. WOT, trimmed correctly, Im getting 7-8 psi. Trimming, I gain 2-3 lbs. I ran with regular gas this summer & motor would hit 1200 degrees before 8000 rpm's. I have always run Avgas (leaded fuel), which always helped on temp. I ordered another 50 gallon drum & will be ready for testing, next spring. I think I am sucking air, since I changed the water pump to 3/4. I did not add cocking last time I changed the pump. Same lower on my Awesomecat, 1/2 water pu. = 15-20 psi water pressure. This is why I am looking for another lower. Don't want to remove from one, change pumps & install on the other. Big pain in me behind Once I get a new lower, Avgas, then the set up will start. Avgas in a 260 center horn works great!! 7-8lbs should be more then enough, the water may be leaving the heads too fast and not actually cooling anyting.

Author:	Hounddog [ November 20th, 2012, 4:23 pm ]
Post subject:	Re: Best lower for drag
stv92 wrote: I have always run Avgas (leaded fuel), which always helped on temp. I ordered another 50 gallon drum & will be ready for testing, next spring. I ran 100-Low-Lead or 100-LL. 100-Low-Lead actually contains more than FOUR TIMES the lead which was in Sunoco-260, one of the highest-octane fuels ever produced for street-use automobiles. I had to run leaded Avgas in my 427 Corvette in the late 60's... 12.5 to 1 compression.. I later ran leaded Avgas in my 70's race Mercury outboards. When the no lead Avgas came out, I switched to it in the outboards. It actually ran COOLER than the leaded Avgas and much cooler compared to other race fuels like VP. If you look at the spec sheets for the older V6 racing Mercurys, they suggested unleaded Avgas. I don't know if you have tried the unleaded, it is less costly and it may? be equal or better.

Author:	Jeff Yammer [ November 20th, 2012, 8:54 pm ]
Post subject:	Re: Best lower for drag
How much compression are you running on a cranking test cold. ? You need to run the stat replacement washers in the heads. As well youre talking about EGT and not motor temp...... that's one serious air leak to get that high EGT at that low temp. Why is your idle at 1800rpm ?

Author:	stv92 [ November 21st, 2012, 9:59 am ]
Post subject:	Re: Best lower for drag
Comp., depends which heads Im running. For break in, Im running low comp heads. Have not put the high comp heads since the rebuild. This motor was set up to drag from day one. 1996 it won proclass,(Alabama drag). Set up to turn 10,000rpm, & was a strong runner (we were running a preloaded lower & had great water) My old mecanic (JW Carboni), rebuilt the motor about 2 years ago. Since then I have only "lake ran" the boat. (break in only) I am starting back at square one with this boat. Yes, Im hitting 1100-1200 degrees (exhaust) at about 8000 rpms, 8000 rpm, I have 7-9psi water I may put the t-valve back on & see what happens. I don't want to play to much with it until I get avgas. Have not run Avgas since it was rebuilt. Was told timing was all the way up, Going to wait till next spring before I can try again,, I changed the ecu so dont know what curves this one has?? Going to send it out this winter to see what I now have, Any ideas will help Jeff

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