454 Project Tow Beast


Well I finally decided to do another TBI project.  This time a 454.  I didn’t need a big dually truck and that would be hard to fit on a dyno anyway.  So I found this nice completely stock 1991 454SS which has the same engine as all the other 454 TBI trucks just these made 20 more hp and torque because they got factory dual 2.5″ exhaust from the factory.  This truck is very stock with original catalytic converters and even still has the smog air pump.

Initial impressions, it feels wimpy for having a 4.10 gear with that little 28″ tire.  But the initial dyno numbers were better than expected.  (Red Graph) Pulling 190hp and 265lb of torque at the rear wheels.  This truck has the heavy duty 4L80E and heavy 14 bolt 9.5″ rearend so its guzzling a good 25% worth of its hp which puts the flywheel numbers at 253hp and only 353lb of torque although that torque number could be off a tad because I couldn’t get a good pull in the lower rpms on this dyno.  don’t know if it was something with the trans or what but had a terrible flare right at the beginning of the pull regardless of what rpm I started the pull right at 3000 rpm it would flare up like shown.  so with the wimpy cam GM put in these things that torque peak could easily be closer to 2500 rpms and falling steadily until that graph catches up.

Anyway this truck happened to have a Jet piggy back chip part number 29118-S and while I have there programming on file and didn’t expect much, I made a couple pulls with it (green graph) and peak hp it actually made 2hp less than the stock chip did however signifcantly beter torque at least to 4000 rpms.  But down around that 3000rpm mark it did make a good 20hp and 35lbs of torque more than the stock chip which is likely where they got their advertising numbers from.   Then I put my towmaster chip in (blue graph) and my torque numbers were a good 10lb over the Jet chip and horsepower numbers at peak were 20hp different but only about 5hp difference down at that 3000 number but dramatically better than stock.

What I find interesting is while we all know these TBI engines are pathetic, I have a stock 1999 7.3L turbo diesel project that i did a few years ago. www.tbichips.com/powerstroke.htm and it pulled 172hp and 278lbs of torque at the rear wheels for very little difference.  Stock versus stock anyway.  Now the chipped 7.3L quickly put the 454 to shame and modern diesels like duramax and cummins are putting out some big numbers stock.

So what am I going to do for this project.  Well, GM didnt make many 454SS trucks.  I just used one because I didn’t need a BIG truck clogging up my driveway.  Most of my 454 customers are 1 ton, suburban or motorhome customers, so I am going to build a torquey TOW beast.  while I don’t think I can quite get modern diesel torque numbers, I am going to try to get close.  I got some inspiration from this engine setup listed in car craft magazine. http://www.carcraft.com/techarticles/ccrp_0803_big_block_cylinder_heads/viewall.html  while they used a 496ci engine which would be nice and a little more cam than I would recommend for a tow beast they made GOOD numbers even with stock peanut port TBI heads.  I was mainly interested in their 5000 rpm numbers as that is as much rpm as you really should be turning a TBI motor and TBI heads on their 496 made 516hp and 543lb of torque. (made a peak torque of 595lb at a crazy low 3200 rpms) The edelbrock heads like used on jims 454 project http://tbichips.com/?page_id=106 made 559hp and 618lbs of torque at 3800 rpms in the 496 build so only about 40hp gain but a noticeable torque increase. The best head they tested was the brodix which at 5000 rpms made 569hp and 626lbs of torque at 4000 rpms. This got me thinking that I should be able to pull right at 40hp less than Jims project with the stock heads. I think it could possibly do better than that due to the intake Jim used I think restricted his engines potential. The flow numbers for the TBI 454 head are:

GM 236 Iron Peanut Oval Port 2.06/1.72-inch valves
Valve Intake Exhaust Lift (w/pipe)

0.100 56 44

0.200 125 90

0.300 183 117

0.400 215 139

0.500 233 158

0.600 235 166

0.700 235 172

Those flow numbers are nearly identical to the LQ4 heads on my 364ci dark nite proect truck www.harrishighperformance.com/dknite.htm  which made 326rwhp and 321lb of torque from that little 364ci engine.  So 90 more cubic inches shouldn’t need quite as much cam to pull off that hp number and those 90 cubes will dramatically help squash the torque number.

LQ4 head flow.

Stock 6.0 Heads

Chamber 71.0 cc 0.100 0.200 0.300 0.400 0.500 0.550 0.600
Intake ??? 66 142 196 228 236 238 240
Exhaust ??? 59 104 137 155 167 173 177
Valve Diameter Intake 2.00″
Valve Diameter Exhaust 1.55″

So whats the PLAN.  But see update below on my screwup ordering the roller cam setup in this truck. Now that the project is finished, I really wouldn’t recommend going this extreme unless your changing heads too.  Based on the final dyno numbers the stock throttle body and intake should have been just fine and I would probably just use a flat tappet cam at that power level.

Edelbrock 3764 TBI intake as I don’t like the HEAVY iron mess GM installed that holds too much heat and I am having Vic at rvmorsemachine.com bore it to match a 54mm bored 454 TBI unit which he will bore out for me as well for this project.  On the air cleaner, I am going to run spectre air cleaner. http://www.jegs.com/i/Spectre/865/47622/10002/-1?parentProductId=1348308 RED or BLUE http://www.jegs.com/i/Spectre/865/47626/10002/-1?parentProductId=1348308 with Hypertech powercharger http://www.jegs.com/i/Hypertech/533/4001/10002/-1  This setup is the best configuration so far that I have tested.  This will get the air to the motor.  For cam, I am going to get a bit expensive here since I am not spending $2000 on a set of aftermarket heads.  Flat tappet cams are obsolete technology.  roller cams like the one car craft used will pull good power numbers with a mild profile.  I am going to use http://www.summitracing.com/parts/lun-20110710k which is the retro roller cam kit with valve springs, timing chain set, pushrods, retro roller lifters, the roller cam with spec 211/219 duration @ .050 with a nice .550/.550 lift with 1.7 rockers which should hit the sweet spot on the head flow numbers. on a TBI compatible 112 LSA.  To further enhance this engines capability, I am going to use a nice set of comp cams 1.7 chromoly full roller rockers. http://www.summitracing.com/parts/cca-1620-16  which is the same rockers used on the car craft engine.  I could use some cheap stainless ebay 1.7 ratio roller rockers off ebay at half the cost but I have never had one of these comp cams rockers fail. This pretty much takes care of the changes to the engine.

In addition, I will be upgrading the stock fuel pump and fuel pressure to the 18psi as I would would one of my custom chip kits and I am going to remove the mechanical fan and replace with electric as mechanical fans like flat tappet cams are obsolete technology and wasting power turning that thing.  I am also going to run a 25% underdrive crank pulley to free up some additional power.

All of this should not only make a significant increase in the power from this engine but also in how efficient the motor is.  This project will also let customers know if spendintg approx $2300 on all these upgrades is going to give them the results they need from their big block engines.

First off, I snagged a used 454 throttle body off ebay and sent it out to www.rvmorsemachine.com to get bored to 54mm for some decent air flow for this big block project.  I put some pictures here as I sent Vic one NASTY looking throttle body and as usual, the unit was transformed into a work of art.  Truly beautiful unit.

Now the returned transformed new UNIT.

I sent RVMORSE the $300 edelbrock 3764 intake to get bored to match as well.  Around $275 for TBI base and intake bored.


Ordered the rest of the stuff from summit racing.


comp cams 1620-16 ultra pro magnum roller rockers $319.97

Hypertech power charger (salad bowl)  $37.25

Jet Fan Switch 60601 to turn on my electric radiator fan. $42.71

Lunati LUN-20110710K retro roller cam setup. $899.95  That one hurts but you get a lot of stuff like the pushrods and valve springs and such.

Spectre 47622 air cleaner assembly $99.99 this price has sure gone up in the last year but best unit I have tested to date.

Also purchased under drive crank/alternator pulley setup off ebay for $72

Lincoln town car radiator fan that I am going to adapt to fit in the factory 454 shroud (I will have pictures). $55


Total so far $2101.87  so that is quite a risk but really looking for a nice reward for that money$$

Update for project tow beast:

Well I lacked some motivation to get this project down because my brother decided to tear up his 1992 454 Dually truck and found a lot of issues with GEN V 454 motors that just killed my motivation for my project truck.  The roller cam setup does cure several of those issues though.

My biggest screw up was ordering that cam kit from Summit and then waiting 3 months to put it in.  Reasoning is pretty simple.  I found that Lunati roller cam kit on ebay and was a nice complete kit with valve springs, pushrods, lifters, and timing chain set and even cam button.  well I put that part number in on summit and it came up as the same price as the ebay seller and so I ordered from summit.   Well 3 month later when I worked up the motivation to tear into this engine, I opened my box and found just Cam and Lifters only.  Before calling Summit and raising hell I looked more closely at their description of that part number and it said Cam and Lifters. So I had no one to scream at but myself and I hate that.  Cost me $340 to order the other part numbers that were listed in the ebay sellers listing so looks like the best place to get this cam kit is on ebay.

That said though, the roller cam setup solves several of the issues that I found with my brothers Gen V 454.

1. GM put wimpy 5/16″ pushrods that bend at the slightest stress like a decent .500 lift cam trying to open big block valves.  roller cam kit comes with 3/8″ hardened pushrods which can withstand a BIG cam.

2. Stock valve springs are also bad to float valves at over 4500 rpms which roller kit has new roller valve springs matched to cam.

Now what the kit didn’t cure on a GEN V 454. These motors have non adjustable valve train.  So I had to order some 7/16 rocker arm studs.  Well these motors don’t take a standard set of studs. (I have a set for sale now for $50) and so I had to order the special set as the hole in the heads is only 3/8″ so comp cams 4514-16 is the part number for those special studs. I had already ordered the comp roller rockers but you would have to use another part to utilize stock rockers and so I wouldn’t spend that money.  On my brothers truck, I got some cheap stainless 1.7 roller rockers for like $125 instead of the high dollar comp cams rockers I used on this project.  But these upgrades cause yet another problem.  Those GEN V stock valve covers are short. real short.  About 3/4″ too short with upgraded valve train.  I found the cheapest tall aluminum valve covers I could find for like $60 a set of ebay and seems to work fine other than with stock crappy iron intake it will interfere with EGR valve.  With edelbrock intake that valve is relocated and its fine.  Hopefully final issue with the GEN V motor, is if you go with 3/8″ pushrods well stock guide plates are 5/16″ so I got the part number off one of GM Performance parts 454 engines for 3/8″ guide plates and ordered 8 of them from summit racing. GM part number 12562369.

Inspired by this video sent to me by one of my customers, http://www.youtube.com/watch?v=i2DvnoHWagk  I have modified the Edelbrock 3764 intake to see if I can gain more power from this combination since my power goal of 400hp at the flywheel is a BIG gain over the 250hp these motors made stock.  I cut a about 1.25 ” notch about 3/4″ deep between the 2 throttle bores and then tried to knife edge what was left in the notch.


Ok so how did it do.   Really nowhere near the number I was expecting.  The Torque number wasn’t too bad.  After it settled in from the initial throttle hit just like the first dyno graph the torque number settled in about 355lbs  or so at the rear wheels or (473lbs at flywheel) which is dramatically better than the stock pull of 265lb and even the chipped dyno numbers of 290lb for a 25% increase in torque which is most definitely apparent when driving the truck.   As for horsepower thats where the problem lies. The graph you can see is just flat instead of having a nice arch to the power curve.  Spent hours trying different air fuel ratios and different timing curves with very little affect on that graph.  Peak came in right at 260rwhp but made right at 200hp right when it settled in at 3100 rpms. so power was up right at 50rwhp across the whole rpm range as wellfor a 25% gain in horsepower as well which really woke the truck up from a driving stand point but that power should have had a bit more climb to it and pulled at least 300rwhp and can’t figure out why.  Its not on the intake side.  I watched the MAP readings with the laptop and the map stayed nice and high and never dropped indicating a restriction.  If anything the bored throttle body was too large for the combination.  I haven’t messed with the stock exhaust which could be a minor contributing factor but the SS does have factory dual exhaust and someone had removed the mufflers so there is just tailpipes after the cats.  the cats could be clogged I suppose but graph typically gets all wonky if the back pressure is too high.

However, this would make a great towing engine which is the name of the project. The torque is great and low rpm power is awesome.  Power just doesn’t climb past 3000 rpms as much as I had hoped.  The 454SS truck is a blast to drive.  Really needs a wimpier gear in the rearend as that 25% improvement in power with a 4.10 gear and 28″ tall 275/60R15 tires just turns them into smoke even on a 20mph roll.  About a 3.42 gear would be great in this truck which would dramatically help its fuel economy.  The electric fan turned out well and the alternator still charges just fine with the 25% underdrive pulleys installed.  Not going to say successful project but its an informative one.  Like I said above, if your not going to change the heads, just run the stock intake, throttle body and stick with a flat tappet cam and spend that money towards exhaust.  The fuel pump upgrade did prove to be needed though.  I started with 15psi of fuel pressure but had issues with fuel around 4600 rpms and so I went to 18psi of fuel pressure and then cut the fuel back in the chip and the air fuel ratio was easier to control although that didn’t affect the dyno numbers a bit.

GM Fuel injection for the average guy