PDA

View Full Version : More horsepower?


Brian B
05-31-2011, 04:33 PM
Are there any HP benefits to opening up the exhaust on LT1 boats? I wouldnt mind a little more sound, but could also use some more power. With modifications to the exhaust, will I need to reprogram or piggyback the ecu?

330hp Indmar X10

Any easy hp mods input is welcomed!

(I rode around in my friends PWT XStar all weekend and was spoiled)

GT500 MC
05-31-2011, 04:36 PM
Where's Hooligan???

JimN
05-31-2011, 04:51 PM
Are there any HP benefits to opening up the exhaust on LT1 boats? I wouldnt mind a little more sound, but could also use some more power. With modifications to the exhaust, will I need to reprogram or piggyback the ecu?

330hp Indmar X10

Any easy hp mods input is welcomed!

(I rode around in my friends PWT XStar all weekend and was spoiled)

It's not going to open much more than it is. Since it's not closed loop, there's no data from the exhaust stream to verify any changes to the tuning.

Brian B
05-31-2011, 07:53 PM
It's not going to open much more than it is. Since it's not closed loop, there's no data from the exhaust stream to verify any changes to the tuning.

Man! I'd kill for another 20 hp! Anyone put blowers on these things aftermarket?

agarabaghi
05-31-2011, 08:21 PM
This total reminds me of the post where a service mechanic told a customer "If you haven't driven your boat with the bigger motor, then your motor is just fine."

What about changing prop? Why do you think you need more power?

ShamrockIV
05-31-2011, 08:23 PM
man u dont want it louder if u are ever gonna surf or board behind it

Brian B
05-31-2011, 08:29 PM
This total reminds me of the post where a service mechanic told a customer "If you haven't driven your boat with the bigger motor, then your motor is just fine."

What about changing prop? Why do you think you need more power?

Already running a power prop.

Brian B
05-31-2011, 08:30 PM
man u dont want it louder if u are ever gonna surf or board behind it

That would be about the only time I wouldnt like the louder exhaust. Currently working on a system with tower speakers so neither would compliment each other......I know.

ShamrockIV
05-31-2011, 08:47 PM
man ur first post says lt1. u have the ltr right?

josepcedwards
05-31-2011, 08:48 PM
Where's Hooligan???
BAHAHAHAHAHAHAHAHAHAHAHAA!!!!! We need his number!

JimN
05-31-2011, 09:02 PM
Man! I'd kill for another 20 hp! Anyone put blowers on these things aftermarket?

You don't put a blower on a motor with higher than normal compression. If you want a cost-effective engine swap, sell your LT-1 and get a 350 Ramjet crate motor. That puts out 350HP and 390 ft-lb of torque.

Brian B
05-31-2011, 09:12 PM
u have the ltr right?

Yup!......

Miss Rita
05-31-2011, 10:32 PM
I'd kill for another 20 hp!

Don't pull out your ninja sword just yet. Twenty horsepower would barely be noticeable. You might gain 1 mph, or lose 0.1 second off your 0-30 time.

If there was any easy horsepower to be had Indmar would have found it a long time ago.

06' X-2 R8R H8R
05-31-2011, 10:37 PM
Buy a SPEED boat....DUHHHHHHHH

east tx skier
05-31-2011, 11:23 PM
Didn't Indmar have a different cam on the 98 S&S that was supposed to give it 350 hp?

Agree with 20 horsepower not being too noticeable on the top. I'd rather have more torque with a more mild increase in hp.

1redTA
05-31-2011, 11:32 PM
change the 48mm throttle body with a 52mm unit
take the throttle body coolant hose of the TB and re route it to the steam port for the heads
gasket match the intake manifold
swap the heads with some ported heads from Llyod Elliot or advanced induction
put a CSR electric water pump over the factory pump
swap a stealth ram intake manifold for the lt:-( this mod requires some real machine work!!!
slap a small shot of nitrous

JLeuck64
05-31-2011, 11:49 PM
Didn't Indmar have a different cam on the 98 S&S that was supposed to give it 350 hp?

Agree with 20 horsepower not being too noticeable on the top. I'd rather have more torque with a more mild increase in hp.

Yes that is what I have heard also. I must say mine does have a lopy idle like any engine with a longer duration cam would have.

I have also heard a rumor that there was a special tune just for the boats that went to Sea World that really woke up the LT-1 but have never confirmed it... maybe Engine Nut could chime in "off the record" to confirm?

JeromeM
06-01-2011, 12:03 AM
**thread jack alert**

sorry, didn't think we needed a new thread. i have a 99 PS205 LTR with the weird spark arrestor as an air filter, can i swap that out for a K&N and maybe improve airflow?

Miss Rita
06-01-2011, 12:19 AM
I have a 99 PS205 LTR with the weird spark arrestor as an air filter, can i swap that out for a K&N and maybe improve airflow?

Yes, the air flow would improve, but you wouldn't notice the difference.

airdrew99
06-01-2011, 09:35 AM
Brian B,
I don't know much about the LTR engine you have, but I've always heard in cars that you will never feel a difference when you add only 20hp. If you happen to go into the motor, you could always port & polish the heads and intake runners for a small gain in hp. Most stock heads have very rough castings which affects the airflow characteristics. You may be able to swap the camshaft for a little more aggressive one, but I'm not 100% sure because it's a boat application. I know in muscle cars you can go with a more aggressive cam to get hp increase, but boats are different because of RPM and you don't have "gears" to go through. I hope this helps a little or gives you a little to think about.

Drew

Brian B
06-01-2011, 01:59 PM
Thanks guys!

I very well understand engine dynamics and have built a handful of race engines (Automobiles). The reason I ask here, is because I'm new to boat performance and their ins and outs. I have a low hour engine and wouldnt consider pulling it, or the heads for that matter. I was just hoping there might be some bolt on's out there that would boost the engines performance a little.......

No go on an exhaust system huh?

timvan
06-01-2011, 02:08 PM
No go on an exhaust system huh?

not much to the exhaust system as is.. you can pull the silencer and replace with pvc pipe as it runs pretty cool. Most guys on here will bash you for it, but its your boat...do as you want.

I did it to a previous mc and noticed minimal gains, seemed quicker out of the hole with better throttle response...but who really knows as I didnt have a way to measure before and after results.

JimN
06-01-2011, 02:32 PM
Thanks guys!

I very well understand engine dynamics and have built a handful of race engines (Automobiles). The reason I ask here, is because I'm new to boat performance and their ins and outs. I have a low hour engine and wouldnt consider pulling it, or the heads for that matter. I was just hoping there might be some bolt on's out there that would boost the engines performance a little.......

No go on an exhaust system huh?

The exhaust can't be made much more free-flowing and any improvements will be slight. The rest can be thought of in terms of a car/truck engine- make it breathe better and it'll go faster. However, there's a fine line between just right and too much power/torque with a given prop. The porting and polishing is always a good idea but I'm not sure I would do it unless the heads & intake were already coming off. If you can do real-time diagnostics and programming, that's definitely one place you could make some power improvements but to really do it the right way, exhaust gas temperatures and emission specs are needed.

etduc
06-01-2011, 03:54 PM
Thanks guys!

I very well understand engine dynamics and have built a handful of race engines (Automobiles). The reason I ask here, is because I'm new to boat performance and their ins and outs. I have a low hour engine and wouldnt consider pulling it, or the heads for that matter. I was just hoping there might be some bolt on's out there that would boost the engines performance a little.......

No go on an exhaust system huh?
They claim 10% increase on horsepower and torque. Just like car engine, near equal length exhaust runners(headers).
http://www.hitekmarine.com.au/hi-tek.htm
or
http://cgi.ebay.com/ebaymotors/3-00-INTAKE-SINGLE-TORNADO-FAN-GAS-FUEL-SAVER-ALL-GMC-/250826435960?pt=Motors_Car_Truck_Parts_Accessories&hash=item3a666bad78