GreyGoose006

hey,

what are the advantages of a better ignition (msd, for example) and how do you install it?

i saw another thread talking about using one for better economy, but i was curious if it really did help or what.

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72chevelleOhio

A friend of mine went from 7-10 mpg to 10-13 mpg on a pretty wicked 406 in a chevelle.
I never tried to run an MSD on the street..

MrPbody

MSD - "multiple spark discharge"

What that means, is at lower revs, you get more than one spark at each cylinder when it "fires". An increase of efficiency comes from a more complete "burn". Beyond 3,000 RPM, it acts more like a "conventional" system.

The brand name "MSD" is among the better quality and more innovative brands out there. They have a multitude of attachments and styles. No doubt, they have a system that can help your particular needs.

For high-revving racers, a "ball bearing" type distrbutor (particularly Chevys, as they have a relatively long distributor shaft) helps aleviate spark "scatter". The oil pump can also put a "pulse" into the distributor shaft, wreaking even more havoc. The MSD and Mallory distributors are te better ones out there. Problems have been reported for Accell over long-tem use.

The MSD "system" (among others) also has available an amplifier that increases the intensity of the spark, as well as offering electronic rev limiters. Good stuff!

Jim

Morley

An aftermarket ignition would be wasted on a stock engine, especially a TPI. The GM HEI is good up to about 5500-6000 RPM, the TPI system starts running out of steam around 4800 RPM. Also, you won't find a more reliable, durable or simpler everyday ignition system than the HEI.

GreyGoose006

i guess i was thinking of a spark amplifier type device.
the engine is not stock btw, its a 350 with about 400 crank hp.
the TPI is the major bottleneck in the system if i understand correctly

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Morley

It is. Especially if it is the stock TPI setup. I also have an 85 IROC (original owner) that I have transplanted a 350 I built into it. The engine is putting out around 400 hp and is NOT running the stock TPI but it is running the factory HEI without any problems. For induction I have ported SLP siamesed runners mated to a port matched plenum on top with a 52mm throttle body. On the bottom of the runners is a port matched Accel superram base. The only ignition "mods" I have are an Accel super coil and Accel spiral wound core plug wires. With all of this the engine can spin to maybe 5500 RPM before power drop off, still within the HEI's operating range.

GreyGoose006

hmmmmm.
i have heard that the slp siamesed runners and manifold package deal thingamabob significantly hurts the bottom end grunt. below 3000rpm i gather.
is this true?

another guy i read an article about did his own porting of the stock runners and intake and said the same thing.

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Morley

On a stock engine, yes it is true because you will loose velocity of the incoming air. Even on a better engine it is true to an extent, but the effect is hardly noticable. The whole idea behind those larger intake systems is to get more air in to allow the engine to rev higher. With a higher performing engine the velocity loss will be more than off set by the ability to breathe better at 5k rpm's and up.
The TPI setup is by far not the best induction system for an engine (but it sure does look purty all polished up). It was designed to run on the street where low end torque is most valuable. There were some improvements made to the system but they can only do so much. If you want a better system look into a modified LT1 intake from LT1intake.com

GreyGoose006

I'll look, but that sounds pricey. Plus, it sound dumb, but one thing that sold me on the camaro was the sexy runners of the tpi setup. I think that is the one time I have ever put form so far ahead of function.

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Blue Bowtie

Don't be too quick to condemn the TPI system in general. Some people have been making pretty serious N/A power with TPIs all the way to 6,300 RPM and beyond, like this crew:

380 RWHP TPI

If you look at the dyno graphs, the torque at the lower end is really nothing like what anyone would call "low" by any means. Certainly not down to the level of an import or Ford 302.

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GreyGoose006

well thats no suprise considering that the whole point of the TPI was to give the 305 the same low end torque as the bigger brother 350 witht the TBI.

TPI is a torque maker for street power.
it is great on a 305 or smaller NA engine, but as soon as you pump up the cubes it runs out of steam quickly.

on a stock 305, it pulls hard up to about 4800 rpms
on a stock 350, it pulls to about 4000 because of the increased flow of air being demanded.

right now, i am looking at a super ram, but the LT4 sounds nice too.
i guess i have to decide weather i want torque or power lol.




besides, 380 rwhp isnt really that impressive. especially from a 350.
my 350 tpi setup (no siamesed runners) is putting about 400 hp to the crank, and thats with mismatched parts off the shelf.
im planning on rebuilding it to take advantage of the engine and cam/heads
thats what happens when you buy someone elses project though i guess

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