Magnuson 2650 pulley combo and hp/boost?

ULTRAZLS1 · 07-29-2025, 03:32 PM

going to the boost side. Got a 2650 coming. built shorblock. i will have enough fuel to run full e85 up to about 900 rwhp. Full DI no port

I have asked a couple people about combos and just wanted a few more opinions before i buy the kit.

Im doing the 10 rib kit with lt5 tensioner.

I was told to go with the 9.2 15% lower and 85 mm 6% upper. To get me around ~17 lbs and ~850 rwhp range

-Magnuson 2650
-Stock lt1 heads with lt4 gaskets
-Built short block with 11.5 compression
-stage 2 cam (dont know specs atm but its medium size still can use stock TC, 6800 or so shift points)
- full catless exhaust with 2 inch headers
-103 tb and 5 inch intake
-full e85 all DI

Like i said just looking for the pulley combo to be 850 rwhp range on full e85. Can do more on a mix etc but i think that should be plenty for now. Raceweight will be 35-3600 with driver after adding blower components. Car was under 3400 with driver NA.

thanks for the insight

tortilla-flats · 07-29-2025, 03:50 PM

In to hear feedback on this. Nice sounding build!

KingLT1 · 07-29-2025, 04:27 PM

With that compression I bet you hit that power goal with 14-15psi. I would probably start with the 90mm upper. That point and half compression makes up for 2-3 psi compared to a stock compression LT4.

Far as cooling, the Magnuson stuff is plenty sufficient combined with the expansion tank.

ULTRAZLS1 · 07-29-2025, 05:18 PM

Quote:

Originally Posted by tortilla-flats

In to hear feedback on this. Nice sounding build!

Quote:

Originally Posted by KingLT1

With that compression I bet you hit that power goal with 14-15psi. I would probably start with the 90mm upper. That point and half compression makes up for 2-3 psi compared to a stock compression LT4.

Far as cooling, the Magnuson stuff is plenty sufficient combined with the expansion tank.

Thanks!

First time going boost so I appreciate any input

ULTRAZLS1 · 07-29-2025, 05:40 PM

Btw king I messaged you back but said your box is full

KingLT1 · 07-29-2025, 05:53 PM

Quote:

Originally Posted by ULTRAZLS1

Btw king I messaged you back but said your box is full

I just cleared it out.

*Joshinator99* · 07-29-2025, 07:36 PM

Quote:

Originally Posted by KingLT1

With that compression I bet you hit that power goal with 14-15psi. I would probably start with the 90mm upper. That point and half compression makes up for 2-3 psi compared to a stock compression LT4.

Far as cooling, the Magnuson stuff is plenty sufficient combined with the expansion tank.

And to build off that, I’d recommend the OP run as close to full E as possible. That compression ratio plus 15+ pounds of boost will call for as much octane as you can run. Just my 2 cents.

ULTRAZLS1 · 07-29-2025, 08:32 PM

Quote:

Originally Posted by Joshinator99

And to build off that, I’d recommend the OP run as close to full E as possible. That compression ratio plus 15+ pounds of boost will call for as much octane as you can run. Just my 2 cents.

My system will support 880-900 full e85 from what my tuner has seen

I haven’t bought the short block yet. I could easily back off the compression. I just didn’t see it as necessary under 1000 hp on my build running full e85. But I could be missing something? I know compression can be good as well to a point. I’m coming from na my knowledge is limited on boost

*Joshinator99* · 07-29-2025, 08:56 PM

Quote:

Originally Posted by ULTRAZLS1

My system will support 880-900 full e85 from what my tuner has seen

I haven’t bought the short block yet. I could easily back off the compression. I just didn’t see it as necessary under 1000 hp on my build running full e85. But I could be missing something? I know compression can be good as well to a point. I’m coming from na my knowledge is limited on boost

Your build sounds fine but you really shouldn’t run that combo on pump gas with that compression ratio & boost combo. So if you’ll always be on mostly full E85 you’ll be fine.

ULTRAZLS1 · 07-29-2025, 09:12 PM

I’ve got e85 all around me that typically is at 76-79. I’m coming from a 14.1 compression 630 rwhp na setup.

*radz28* · 07-30-2025, 07:11 AM

Are you from LS1tech?

ULTRAZLS1 · 07-30-2025, 12:54 PM

Yes

Saberscar223 · 07-30-2025, 02:37 PM

What fuel upgrades do you have? Im trying to get to the point where I can comfortably run full E85 at around 700whp. I was thinking LT4 fuel system with my 32% Cam lobe would be enough.

ULTRAZLS1 · 07-30-2025, 03:18 PM

Quote:

Originally Posted by Saberscar223

What fuel upgrades do you have? Im trying to get to the point where I can comfortably run full E85 at around 700whp. I was thinking LT4 fuel system with my 32% Cam lobe would be enough.

Goliath hpfp with xdi +50% injectors. LT4 in tank pump with a dsx aux pump. Cam with 38% lobe.

With full e85 youll need the aux pump for low side. dsx 320. Those support 1000rwhp range. There are other options as well. I think your in tank pump is already lt4 style being a new SS. But im not certain.

I think the lt4 injectors and hpfp will support 700 rw on full e85. More on a mix.

mine (lt4 hpfp and injectors) are going to be for sale very soon. About 5000 miles. If you are interested.

07-29-2025, 03:32 PM	#1
ULTRAZLS1 Drives: 14 Silverado LTZ Z71, 16 Camaro SS Join Date: Nov 2009 Location: Jackson, Michigan Posts: 4,423	Magnuson 2650 pulley combo and hp/boost? going to the boost side. Got a 2650 coming. built shorblock. i will have enough fuel to run full e85 up to about 900 rwhp. Full DI no port I have asked a couple people about combos and just wanted a few more opinions before i buy the kit. Im doing the 10 rib kit with lt5 tensioner. I was told to go with the 9.2 15% lower and 85 mm 6% upper. To get me around ~17 lbs and ~850 rwhp range -Magnuson 2650 -Stock lt1 heads with lt4 gaskets -Built short block with 11.5 compression -stage 2 cam (dont know specs atm but its medium size still can use stock TC, 6800 or so shift points) - full catless exhaust with 2 inch headers -103 tb and 5 inch intake -full e85 all DI Like i said just looking for the pulley combo to be 850 rwhp range on full e85. Can do more on a mix etc but i think that should be plenty for now. Raceweight will be 35-3600 with driver after adding blower components. Car was under 3400 with driver NA. thanks for the insight

07-29-2025, 03:50 PM	#2
tortilla-flats Drives: 2023 Camaro 2SS Join Date: Nov 2024 Location: DFW, TX Posts: 368 View My Garage	In to hear feedback on this. Nice sounding build! __________________ Camaro SS - (almost) FBO/E85: Tuned by Snackbar Tuning/21st Century Muscle Cars

07-29-2025, 04:27 PM	#3
KingLT1 Drives: 2016 1SS NFG A8 Join Date: Aug 2017 Location: 46804 Posts: 7,641	With that compression I bet you hit that power goal with 14-15psi. I would probably start with the 90mm upper. That point and half compression makes up for 2-3 psi compared to a stock compression LT4. Far as cooling, the Magnuson stuff is plenty sufficient combined with the expansion tank. __________________ 2016 NFG SS A8/Whipple 2.9/Fuel System/Flex Fuel

07-30-2025, 07:11 AM	#11
radz28 Petro-sexual Drives: Ultra-Grin Join Date: Oct 2006 Location: Crazy Coast Posts: 15,850 View My Garage	Are you from LS1tech? __________________ '20 ZL1 Black "Fury" A10, PDR, Exposed CF Extractor Magnuson Magnum DI TVS2650R // RFBG // Soler 103 // TooHighPSI Port Injection // THPSI Billet Lid // FF // Katech Drop-In // PLM Heat Exchanger // ZLE Cradle bushings // BMR Chassis-Suspension Stuff // aFe Bars // Diode Dynamics LEDs // ACS Composites Guards // CF Dash // Aeroforce // tint // other stuffs

07-29-2025, 05:40 PM	#5
ULTRAZLS1 Drives: 14 Silverado LTZ Z71, 16 Camaro SS Join Date: Nov 2009 Location: Jackson, Michigan Posts: 4,423	Btw king I messaged you back but said your box is full

07-29-2025, 09:12 PM	#10
ULTRAZLS1 Drives: 14 Silverado LTZ Z71, 16 Camaro SS Join Date: Nov 2009 Location: Jackson, Michigan Posts: 4,423	I’ve got e85 all around me that typically is at 76-79. I’m coming from a 14.1 compression 630 rwhp na setup.

07-30-2025, 12:54 PM	#12
ULTRAZLS1 Drives: 14 Silverado LTZ Z71, 16 Camaro SS Join Date: Nov 2009 Location: Jackson, Michigan Posts: 4,423	Yes

07-30-2025, 02:37 PM	#13
Saberscar223 Drives: 2023 Riverside Blue 2SS Join Date: Sep 2022 Location: Denver,CO Posts: 278	What fuel upgrades do you have? Im trying to get to the point where I can comfortably run full E85 at around 700whp. I was thinking LT4 fuel system with my 32% Cam lobe would be enough.

User Name		Remember Me?
Password