Megajolt Questions

[Sprintinbits]

Has anyone used the megajolt system on a Sprint engine?
I'm curious which trigger wheel to get and how the sensor is best mounted.
Pics would be a bonus.
Thanks

[Sprint36]

Have a look here:

http://www.autosportlabs.org/viewtopic.php?t=756

David

[Sprintinbits]

Cheers David. I couldn't have asked for more!!
The linked photos make it look so easy.

Does anybody on here run one of these systems?
I am I right in thinking the MAP option is better for all round driveability rather than TP sensor?

[Sprint36]

I've assembled a board (about 3 years ago!) but have never got round to installing it. MAP sensor should be OK on a standard cam, TP is better with wilder cams and individual throttles where a good load signal can be hard to get.

David

[rich]

after reading this thread i've looked into this ignition system and seems pretty good ,

two questions

where can i get the kit in the uk for the best price and how does the tps work/where is it fitted, this bit has baffled me

cheers

rich

[Sprintinbits]

http://trigger-wheels.com/store/index1.html

I've had a good rummage around that site and the US manufacturers site? http://www.autosportlabs.net/Main_Page

The UK site seems legit I might get mine from the US though as I like the idea of soldering it all up myself

[rich]

spent most of last night looking throu the site and trying to take in the wiring diagrams and stuff, came to the conclusion that it would be much easier if i had the parts to hand ,
what there is no info on is were to and how to fit the tps , i have looked at the tps 's and if i understand them right they fit on to the throttle spindle and turn with them and send a bigger signal , abit like a volume control, has any one fitted one to dellorto's if so which one

rich

[rich]

managed to find northampton motorsport who say they have a tps that fits weber/dellorto's,
just waiting to hear on a price and if itplugs into the megajolt .


rich

[Sprintinbits]

That's good to know Rich. Good bit of homework

What are the fundamental differences in operation between MAP and TPS then?
I'm not to worried about the install, I'm more keen to know how the different methods of detection translate to driving on the road?

[rich]

map over tps theory came mostly from sprint36's comments and the fact you have to fit pipes from each inlet into a resovire with the map,i've gor an str91 which could be said to be a bit wilder.
i think the tps is a bit more accurate in knowing exactly what your doing , the map method works on suction and their are lulls and peaks when you dont want them, .
alot of more modern cars have this fitted over the map .
i am no expert though and am working out all this from knowing nothing 2 days ago, may be sprint 36 will enlighten us , i hope

rich

[Sprint36]

Older injection systems used a flap to sense airflow, then hotwire flow sensors were used. Modern cars tend to use MAP and TPS, but TPS is usually only used for detection of certain conditions such as idle or wide open throttle. But modern cars also have thousands (millions?) of lines of code to program them and are not coded for performance so don't copy what you find on a modern production car.

David

[rich]

sprint36 , so why did you say that tps is better than map when using a lairier cam etc .

i've got a str91 with dell 45's thats why i thought i shoud go with the tps.

rich

[DavePoth]

AIUI a MAP sensor will respond to what's happening in the manifold, but if your car is a bit lumpy at low RPM it won't get the correct reading.

[zombeh]

What are the fundamental differences in operation between MAP and TPS then?
I'm not to worried about the install, I'm more keen to know how the different methods of detection translate to driving on the road?

You're trying to work out two things, how fast the piston is moving, so you ignite the fuel/air at the right time so the flame front hits the piston just after tdc

And what the load is like so if you're cruising or idling the revs stay constant and if you're accelerating hard you get as much power as possible.

You can get a very good idea of what the engine is supposed to be doing by looking at the vacuum in the manifold (that is after all what your standard dizzy does) and a good idea of what the driver wants it to do from throttle position. Most ecus use both so you get a good idea of what the engine is doing and what the driver is telling it to do

So ideally you'll get a timing from MAP and RPM then adjust it a bit depending on TPS.

If you've got seperate runners on the manifold with dellortos/webers/throttle bodies on the end then you'll get crazy nonsense from a MAP sensor as you can only easily connect it to one cylinder get a huge pressure change every time an inlet valve closes. So you can't then use that to work out what the engine is supposed to be doing as it'll only give a sensible reading for part of every fourth intake stroke. So you'd have to guess load based on TPS and RPM. This should work well most of the time but won't be ideal. Usually the disadvantages are outweighed by having the precise control over each cylinder that you get with seperate bodies/carbs.

(edited to reflect the fact I've read the thread title as well as the posts in it and we're talking about ignition not fuel injection)

[rich]

WELL SEEMS NORTHAMPTON MOTORSPORT WANT £60 FOR A TPS TO FIT A DELLORTO , A BIT STEEP I FEEL.

while thinking this through i am wondering how to fit the ford coil connectors to sprint ht leads, anyone done this bit.

rich