489ci tow build...

[bucket]

Bucket~The 280 TFS heads are bad to the bone. Eric W... a famous head porter and youtube tested a line of oval heads and the AFR 265 and TFS 280 head makes the best torque in the imdusty hands down. Now you got me thinking about that youtube video/channal.

On the pistons... how much compression can we run MAX and get away with 87 octane ? Gas stations are not consistent and we have to think about detonation...

Yes, I have been watching Eric W's videos a bunch lately.

As for compression, generally speaking aluminum heads will dissipate heat faster and allow for more compression. I've never been fortunate enough to run aluminum heads on a big block (or even a truck) but I have run them on a torquey small block in my Camaro. I run a manual trans and lugging it down in hot weather, I have not experienced detonation. It's been 20+ years since I built it and I don't recall the compression ratio. I think it's close to 10:1.

 

[Bextreme04]

Bucket~The 280 TFS heads are bad to the bone. Eric W... a famous head porter and youtube tested a line of oval heads and the AFR 265 and TFS 280 head makes the best torque in the imdusty hands down. Now you got me thinking about that youtube video/channal.

On the pistons... how much compression can we run MAX and get away with 87 octane ? Gas stations are not consistent and we have to think about detonation...

Factory L29 and 8.1L are in the 9.0:1 range with the factory fast burn iron heads. You can run ~10:1 very safely on aluminum heads and 87 octane. Really, the dynamic compression is going to be the determining factor for pump gas drivability and that is mostly going to depend on the cam. A mild RV/towing cam is going to have a higher dynamic compression that will make it more susceptible to detonation, especially at lower RPM and high loads like you would see in towing operations. You can get away with a very high static compression ratio if you have a very aggressive cam that allows the dynamic compression to bleed down but also only really gets going at higher RPM.

My build is almost completely stock. I took the stock L29 and had it cleaned and inspected. It had 288,000 miles on it when removed from the 97 K2500 Suburban donor. I was able to get the bores completely cleaned up with only a .020" over bore and then used stock replacement sealed power pistons. Final deck height was ~ .003-.005" and I used a factory replacement felpro gasket kit with factory style head gaskets. I think final quench was in the .055" range, which is perfect. Heads were just cleaned up and refreshed. Heads were just surfaced and only took ~.003" off to get flat. I polished the rough flashing off the combustion chambers and polished the exhaust ports. Rough port matched the intake ports to the intake. Only real improvements have been to the cam, valvetrain, EFI system and ignition. I blocked off the factory regulator and installed a remote adjustable one. Converted the injectors to Bosch Gen III 30lb/hr injectors and converted the ignition and ECU to P01 Gen III LS. The moroso coil mount brackets let me use the Gen IV coils from my 2011 LC9 Suburban engine.

Just last night I finished removing some of the unneeded wiring on the factory harness and got the new 3-wire AC pressure gauge ran. Ran the coil wiring across the harness and pinned in the oil pressure sensor so I can read that through the OBD2 scanner instead of just looking at my dash gauge. Still need to finish ringing out the wiring harness and then bundle it all up and secure it to the right spots. Hopefully some time tomorrow I can do a trial fire up of the engine on a makeshift stand before I start swapping everything over.

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[Bextreme04]

Oh, and checking on a compression calculator... my L29 after the rebuild should be ~9.15:1 Static compression ratio and ~8.4:1 dynamic with this cam. It is right on the borderline of what is considered safe towing compression ratios for an iron headed big block, but I also have the benefit of having EFI and dual knock sensors to keep it safe.

 

[Craig Nedrow]

This is my tow build here for my 1987 R20 pickup. I have a 20ft trailer and a 2000 Z28 that i will tow on occasions or as needed. The truck is a camper special model. The truck has a 454/400 setup right now from the factory but it dont handle the weight of a trailer like a big block should. So i want to do a 489ci build that can run on 87 octane and make as much TORQUE as possible under the curve. At 70 mph my truck is at 3100 rpm or so with the 4.10 gears . I have several questions. I have LS knowledge but not big block knowledge.

What heads , cam and intake should i look into ?
Is the Vortec heads better than the peanut heads ?
Who port cast iron heads?
What compression should i be aiming for?

After digging and digging for info i did come across a (article) hand ported vortec headed 489ci engine that made 420hp/555TQ with a 204/214 crane cam.
Should i copy that combo ?

I want/need the truck to pull my car with ease up to LS Fest yearly in Bowling Green Kentucky which is 255 miles each way for me.

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E-Brock oval air gap intake, headers 1 7/8 tube for chevelle, short duration cam no more then 280 ([email protected]) 750 holly. That’s about $1000. Bucks and best bang for your buck. I had that combo and hauled 20 foot trailer with 3 1/2 tons of hay easy, total weight little over 8000 lbs……for years. Excellent throttle response, burnout city. Good proven heads are $$$ forged internals not necessary, stock rotating assembly plenty good. Do the above, and you will love that combo. Down the road and itchin for more, get a top end kit, mid 500 hp and torque. The build above was a I need it build. Build I am doing is an “ old and always wanted it” build. For reference, the AFR 265 were $2600 on sale.