Results after a "profesional tune"

[VL400]

Will be doing a side by side comparo with the spartan when it arrives (5 weeks so far...). I have an LM1, LM2 and MTX-L to test against.

[Gareth]

gee, bad luck with the shipping, mine was in the car in under two weeks, crap time of year?

oh yeah, I should add that the display on the Spartan is a lot easier to read in both daylight and night..

[charlay86]

The biggest issue that stops the ecotecs from making decent power is the stock valves are too small, and they aren't reliable at much over 6000rpm (which is less of an issue considering the implications of the first issue).
small inlet valve is good for low speed torque but it really limits the potential for making power without going to a very long duration cam which kills off the low speed torque....

[vlad01]

Its interesting you say that. A mob in the states called Abbott racing heads. Did a lot of good R+D on ecotec and found that too big valves killed off power in them. Although i recall saying that it helped peak power but hurt power elsewhere making them overall slower engines?

From their 3.8L head research they tested big valves from intake 1.86-1.88 and found the small 1.84 to make the fastest accelerating engines.

This a stock block with their own heads, custom cam and custom exhaust.

Their NA race engine made 270hp @ RW or 201rwKW at just under 6K rpm roughly equal to 350hp at the flywheel.



here is the link anyway. I think most builders struggle to get good power out of them because they are lacking in proper engine development program. Most builders just use off the self parts which weren't developed together to compliment each other.

http://abbottracingheads.com/gm3800.htm

[Holden202T]

in my experience with almost any engine, bigger valves only really start to help for high revs (ie. above about 5000rpm), if its going to be a streeter its a waste of time as what you loose down low is not worth the gain up high, but for a race motor that never sees low revs its certainly worth the larger valves!

[krusty]

in my experience with almost any engine, bigger valves only really start to help for high revs (ie. above about 5000rpm), if its going to be a streeter its a waste of time as what you loose down low is not worth the gain up high, but for a race motor that never sees low revs its certainly worth the larger valves!

Bingo. People commonly get carried away with the bigger is better thing but in an engine/ petrol driven air pump velocity and continuity of flow is more important imo. Standard valves and heads, intake manifold and runners with upgraded valve train can go deep 600hp easily with a turbo or larger no BS charger

[Gareth]

Awsome link Vlad01 thanks for that, spent heaps working that out years ago for a speedway engine we developed, would have been handy back then...

It seems strange to me that a company like that would share that type of data with anyone would have cost a packet in time and money...

[delcowizzid]

the bigger the valve the less velocity over the seat at low lift.the same thing happens when you change seat angles you drop velocity at lower lifts as the valve moves off the seat it gets further from the seat faster with a 30 degree angle v's a 45.ive been playing with port flow analyzer its pretty cool changing valve sizes and seat angles and watching airspeed through the valve as it opens.3/4-full lift valve seat velocity is just slightly above port velocity low lift its way higher than port velocity can see how a bigger valve could drop torque when your playing round in the software

[Holden202T]

yeah I did a rough engine analyser of a 202, and with stock valve size, going up to yella terra size only really made a gain about 5500-6000rpm but killed off low end torque!

[krusty]

yeah I did a rough engine analyser of a 202, and with stock valve size, going up to yella terra size only really made a gain about 5500-6000rpm but killed off low end torque!

See, this just confirms N/A really sucks hahaha. F/I, the solution to all volumetric efficiency scenarios