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Old 10-31-2012, 09:26 AM   #5
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Can I install a hydraulic roller camshaft in my TBI engine? What do I need to know?
Yes, the TBI engine blocks have all the provisions for hydraulic rollers, including the bosses for the spider. Unfortunately, they are not pre-drilled. Therefore, you should disassemble the engine first to avoid getting metal shavings in your engine. There are two terminologies that you have to watch out for here: Retrofit roller cams are for pre-87 blocks: OEM roller cams are for 87 and later blocks. The best way to convert to a hydraulic roller is to buy a kit available from camshaft companies like Comp Cams (K-kit) that includes almost all the parts you need for the swap. The only additional parts needed are the spider, retainer plate, and the roller rocker arms. Total cost however is about $1000.
Read the following article for more info on installing a roller camshaft:

An except from the article: “One of the more budget-oriented conversion kits from GM Performance Parts is the Hot hydraulic-roller cam. This particular cam was originally designed for the LT1 small-block and used 1.6 roller rockers. ... This is a great cam; in a 355ci small-block with Vortec heads and a GM Performance Parts dual-plane intake, it made 412 hp and 422 lb-ft of torque with 9.75:1 compression.”

Is there any way to predict what kind of hp I’d expect from my performance upgrades?
You bet. I did a series of common engine upgrades using the stock TBI engine to illustrate the utility of dyno simulation software. Here’s a link to the thread: Engine sim software is an invaluable resource in helping to choose the right camshaft or the right performance heads. You can also couple your engine with the Drag sim software to see how your engine upgrades will perform on the street. You can try out different rear ends, transmissions, or higher stall torque converter with your engine/truck combo. Spending some quality time with this software could save you thousands of dollars in selecting the wrong parts. I can not say enough about the utility of this software.

What TBI and Vortec intake manifolds are available for my truck?
There are 3 aftermarket TBI intake manifolds that are out on the market today. Holley makes one that has 2” bores but requires you to use an older style EGR. GM performance parts make one that also has 2” bores but is designed to be used with Vortec heads. They will not work with non-Vortec heads since the intake runners are much taller. The only real bolt-on without any modification is the Edelbrock Performer TBI intake. It is a direct replacement for the stock intake manifold with no modifications required. Its only downfall is that it uses the stock size inlet bores that don’t allow you to use a larger TBI unit as previously mentioned. Your local machine shop can make easy work of this and the intake can be bored to accept 2” TBI units. The last option is to use an intake design to work with a carb and use a TBI adapter plate (i.e. GM or Trans Dapt). Some people go this route and have a tremendous amount of success.

The only direct Vortec-compatible intake is the marine version that I mentioned earlier. It allows the use of standard aftermarket fuel injectors. There are also some other modifications that are required to use this intake. The conversion link is here: There is also a Vortec-compatible TPI base manifold available if you'd like to switch to TPI induction.

Are there any other intake systems I could use for my Vortec engine?
Definitely. Some people have moved over to the GM RamJet for Vortec engines. Edelbrock also makes a MPFI system for Vortec heads. More and more manufacturers are making Vortec- compatible intakes and fuel injection systems. A less expensive option may be a TPI conversion ( Visit Summit Racing for an up-to-date listing of Vortec-compatible systems. Weiand, for instance, has their new Stealth Ram for Vortec heads and even the weiand supercharger units for Vortec heads. Any of the products would be used with TBI engines that use Vortec or Vortec-style performance heads as well.

What about Edelbrock’s MPFI conversion for TBI engines or engines with Vortec heads? Is it worth it and how much power does it provide?
Another common question. Here is a good article on this kit: Edelbrock did their own testing using their performance parts (cam, heads, exhaust, etc.) and came up with about 270 hp. I use it, but I’ve matched it with Trick Flow heads and a cam from Comp Cams roller with more duration and higher lift. Here are the pro's and con's on this kit.

1. I called Edelbrock and the supplied injectors are rated at 20.5#/hr at 43 psi. With tuning and maximal FP (~65 psi), these injectors are good up to 360 hp. You can also swap the injectors for larger ones, so you'll never exceed the hp limit of the fuel injectors,
2. Least expensive manufactured MPFI system on the market that's brand new.
3. Single plane intake design that works well with high flow heads/camshaft upgrades. Although torque is lower than a dual plane setup at lower RPMs, torque output is still significantly more than stock.
4. There is an aftermarket adjustable FPR available for it. There are several manufacturers, including Holley, Jet, Automotive, etc. I purchased the Holley one (512-502) and switched the output connector with an AN-6 one (Barry Grant 140028). Easy peasy. There is a schrader valve for a fuel pressure gauge off the driver's side fuel rail. It can be swapped out to work with an inexpensive underhood Autometer fuel pressure gauge. In order to make this work, you'll need to exchange the position of the fuel rails (driver's side fuel rail to passenger's side and vice versa for passenger's side fuel rail) and rotate them 180 degrees (Edelbrock engraving towards manifold). The fuel lines hook-ups will still be at the back, but on the opposite side. You will also need to create an access hole in the throttle cable mounting bracket to easily adjust the AFPR with an allen key.

1. Relatively expensive for the performance gain on stock setup
2. Some improvement in highway fuel economy, but not much.
3. You can achieve similar performance from a TBI/chip for less money BUT you'll need larger injectors to match your power output.
4. Need a custom chip if you use any camshaft or cylinder head other than Edelbrock. The Edelbrock tune is not optimal anyway, and probably explains the poor performance some people have experienced. Save some money by ordering the 3502 kit, which is the same system w/o the Edelbrock-supplied chip.
5. Not a true PFI setup, since the PCM fires the injectors using the TBI firing strategy (twice as often as PFI). For a true conversion, you can use the PCM from a 94-95 truck (7427) and convert it to PFI: A good discussion topic on this can be found here:

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