Procomp/speedmaster heads, fitted and 1/4 results
Thread Starter
Teching In
Joined: Jul 2017
Posts: 18
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Procomp/speedmaster heads, fitted and 1/4 results I am going to write up all the mods I have done to my ls1 and review them, I’ll have this little disclaimer before each of the reviews and results, skip if you have read my past review disclaimers
i have an ls1 swapped 82 Vette, lightened a lot of it (as it sits now with a full tank of fuel it is at 2900lbs.
mods, Howard’s asa cam, home ported 241 heads, shorties with no cats, 2.25”duels, pod filter right on the throttle body (with fresh air duct), 2.87 rear end, mickey thompson 255/60/15 tyres, stock converter
i own a modern Gtech pro (50hz as opposed to most 10hz), and also have 1 mile of tarmac on my property. So I measure my 1/4 mile sometimes 20 times a day.
Here is is a baseline of my results (doesn’t include the times of the mods I will be reviewing and measuring) (I’ll try convert some to imperial, I’m an Aussie so we do metric, and times differ very slightly between the 2, my 1/8th mile is measured from 200m, so might be .05 difference in some spots
60’ 1.98
100kph 4.03
1/8 7.8@95mph
1/4 11.97@118mph
this is the average, some results I have that are slightly better, but I have the advantage with my Vette having such a low gear ratio that I dead hook on launches, so all the 100’s of results and runs I have made (all on “the street”, my asphalt is only as good as standard roads) are all within 0.05secs. I try do all my runs at the same temp and also no tail winds etc. I will be installing a 3200 stall very last on my car, as I think the wheelspin would make it much harder to get consistent results on the street, and I’m just as keen to see the real world results of the msd leads, fast 90 intake, 90 throttle body, powerbond 25% pulley, ported 243 heads, ram air and also the stall. All of which I will be installing in the very near future and will do one by one.
So this is for procomp speedmaster heads, I bit the bullet and got the fully assembled heads that were not cnced but were 62cc, they looked to be a copy of 243 heads, minor differences, but about the same intake and exhaust cc,
my theory behind these is that I don’t trust them, so I’ll do a lot of the work myself, and I noticed the rocker bosses were MASSIVE, 5 or 6 times more material than the standard 243 heads, but that didn’t matter as I was doing a mild port and polish.
i also to it to a head reconditioning place, and got them to do a valve job (not 3 or 5 angle, but that bowl blend bit they use, I guess it is equivalent to a 100angle cut that goes 3” inside the port and also shrouds the cc wall too, as I don’t trust the factory blends.
so, to summarise, I have 243 heads at 62cc, that I ported out and got a bowl blend. I also went with a 0.036” gasket for them, putting my cr to about 11.4-11.5 (hard to say exactly when I shrouded the valves a little)
they are still on and running with no problems by the way. Incase you think “for now they are” has been about 5000miles and have taken it up to 120mph about 4-10 times a day atleast 3 times a week for the last 4 months. And I never show any mercy with my engine.
———-quarter mile results,———
i was slower. On average I was getting 12.2@188kph, I used to get 11.8-9 consistently, and my best we’re 11.5@194, but otherwise I usually get 11.85@193kph.
there we’re a few odd results that gave me a 11.9, but I’m slower.
now though, I have found out a few things since then.
firstly, I had done
some port matching with the intake, I though there must be something wrong with the casting, and that the ports could be a little off, guess what, there were, I matched the ls6 intake to the ports (enough plastic to shave down on all ports) and that got me to 12.05s very consistently at 191-193kph, back to where I was atleast.
but why slower or as fast as my ported 241 heads (I ported both 241 and speedmasters),
few things in play here, one of which could (but probs not) is I upgraded my gtech to one with an external high sensitivity gps sensor that has yaw and pitch integrated, which plugs in and sits in the parcel shelf, I thing it would activate the quarter mile run as soon as the car “squats” at 0kph, as opposed to being on the windscreen with a less accurate sensor, basically I would think the old way would activate when you are going 1kph or so instead. That’s one theory
but the rest comes from the old data I have, I do a lot of tests from 110kph to 180kph, this is because At wot I am in 2nd gear, no gear changes and no wheel spin, no rev limiters etc, so it is a good indicator of power, guess what, I am atleast as fast as my 11.5 run 110-180kph. Showing I am making more power. And consistently does so too. The other fact is that my 330’-1/4 mile is as fast as my fastest runs. Infact the only place where I am slower is my 60’, even from my 60’-1/4 I am as fast or faster than ever.
so my 20m/60ft is slower. Why?
my Mickey Thompson’s are nearly showing camber, getting new ones this month. And am getting wheel spin from 0-30kph, then it bogs down and i start going. I am confident the potential added power is causing extra spin than before I put the heads on, let alone being winter here and the best times before were mid summer (at night, but roads still warm with brand new mickeys).
also I hogged out the intake a lot on the 241’s, made the intake port as wide as I dared, where these 243’s I actually didn’t touch the port size, really was just a clean up and rocker delete. I sold the old 241’s for $200usd less than what the new speedmasters were assembled inc head gaskets and bolts and head work.
i don’t have an ET or mph to show for it, but I don’t have the tyres either, and I do have many fixed gear runs to show I am faster without wheelspin, but not much, my 60ft is 2.3ish, and on my best quarters it was 1.9. Nearly half a second there.
conclusion, the speedmasters did add a little power, not much
They did work for me, no leaks and are fine, but i think your money is better off in actual 243’s, I should have more than the 10hp that these gave (although my ecm has not been tuned for the extra cr), so there is probs more power on the bench, or maybe my 241’s were so good and my first try at porting went better than I thought, so I already had a huge advantage. I am getting new tyres in the next few weeks. Give you a proper comparison. But otherwise, they are alright, not going to tell you if it was worth the time and effort (remember I got new springs, valves, retainers, seals etc too, so that alone may offset the $200. Make up your own mind. Cheers
i have an ls1 swapped 82 Vette, lightened a lot of it (as it sits now with a full tank of fuel it is at 2900lbs.
mods, Howard’s asa cam, home ported 241 heads, shorties with no cats, 2.25”duels, pod filter right on the throttle body (with fresh air duct), 2.87 rear end, mickey thompson 255/60/15 tyres, stock converter
i own a modern Gtech pro (50hz as opposed to most 10hz), and also have 1 mile of tarmac on my property. So I measure my 1/4 mile sometimes 20 times a day.
Here is is a baseline of my results (doesn’t include the times of the mods I will be reviewing and measuring) (I’ll try convert some to imperial, I’m an Aussie so we do metric, and times differ very slightly between the 2, my 1/8th mile is measured from 200m, so might be .05 difference in some spots
60’ 1.98
100kph 4.03
1/8 7.8@95mph
1/4 11.97@118mph
this is the average, some results I have that are slightly better, but I have the advantage with my Vette having such a low gear ratio that I dead hook on launches, so all the 100’s of results and runs I have made (all on “the street”, my asphalt is only as good as standard roads) are all within 0.05secs. I try do all my runs at the same temp and also no tail winds etc. I will be installing a 3200 stall very last on my car, as I think the wheelspin would make it much harder to get consistent results on the street, and I’m just as keen to see the real world results of the msd leads, fast 90 intake, 90 throttle body, powerbond 25% pulley, ported 243 heads, ram air and also the stall. All of which I will be installing in the very near future and will do one by one.
So this is for procomp speedmaster heads, I bit the bullet and got the fully assembled heads that were not cnced but were 62cc, they looked to be a copy of 243 heads, minor differences, but about the same intake and exhaust cc,
my theory behind these is that I don’t trust them, so I’ll do a lot of the work myself, and I noticed the rocker bosses were MASSIVE, 5 or 6 times more material than the standard 243 heads, but that didn’t matter as I was doing a mild port and polish.
i also to it to a head reconditioning place, and got them to do a valve job (not 3 or 5 angle, but that bowl blend bit they use, I guess it is equivalent to a 100angle cut that goes 3” inside the port and also shrouds the cc wall too, as I don’t trust the factory blends.
so, to summarise, I have 243 heads at 62cc, that I ported out and got a bowl blend. I also went with a 0.036” gasket for them, putting my cr to about 11.4-11.5 (hard to say exactly when I shrouded the valves a little)
they are still on and running with no problems by the way. Incase you think “for now they are” has been about 5000miles and have taken it up to 120mph about 4-10 times a day atleast 3 times a week for the last 4 months. And I never show any mercy with my engine.
———-quarter mile results,———
i was slower. On average I was getting 12.2@188kph, I used to get 11.8-9 consistently, and my best we’re 11.5@194, but otherwise I usually get 11.85@193kph.
there we’re a few odd results that gave me a 11.9, but I’m slower.
now though, I have found out a few things since then.
firstly, I had done
some port matching with the intake, I though there must be something wrong with the casting, and that the ports could be a little off, guess what, there were, I matched the ls6 intake to the ports (enough plastic to shave down on all ports) and that got me to 12.05s very consistently at 191-193kph, back to where I was atleast.
but why slower or as fast as my ported 241 heads (I ported both 241 and speedmasters),
few things in play here, one of which could (but probs not) is I upgraded my gtech to one with an external high sensitivity gps sensor that has yaw and pitch integrated, which plugs in and sits in the parcel shelf, I thing it would activate the quarter mile run as soon as the car “squats” at 0kph, as opposed to being on the windscreen with a less accurate sensor, basically I would think the old way would activate when you are going 1kph or so instead. That’s one theory
but the rest comes from the old data I have, I do a lot of tests from 110kph to 180kph, this is because At wot I am in 2nd gear, no gear changes and no wheel spin, no rev limiters etc, so it is a good indicator of power, guess what, I am atleast as fast as my 11.5 run 110-180kph. Showing I am making more power. And consistently does so too. The other fact is that my 330’-1/4 mile is as fast as my fastest runs. Infact the only place where I am slower is my 60’, even from my 60’-1/4 I am as fast or faster than ever.
so my 20m/60ft is slower. Why?
my Mickey Thompson’s are nearly showing camber, getting new ones this month. And am getting wheel spin from 0-30kph, then it bogs down and i start going. I am confident the potential added power is causing extra spin than before I put the heads on, let alone being winter here and the best times before were mid summer (at night, but roads still warm with brand new mickeys).
also I hogged out the intake a lot on the 241’s, made the intake port as wide as I dared, where these 243’s I actually didn’t touch the port size, really was just a clean up and rocker delete. I sold the old 241’s for $200usd less than what the new speedmasters were assembled inc head gaskets and bolts and head work.
i don’t have an ET or mph to show for it, but I don’t have the tyres either, and I do have many fixed gear runs to show I am faster without wheelspin, but not much, my 60ft is 2.3ish, and on my best quarters it was 1.9. Nearly half a second there.
conclusion, the speedmasters did add a little power, not much
They did work for me, no leaks and are fine, but i think your money is better off in actual 243’s, I should have more than the 10hp that these gave (although my ecm has not been tuned for the extra cr), so there is probs more power on the bench, or maybe my 241’s were so good and my first try at porting went better than I thought, so I already had a huge advantage. I am getting new tyres in the next few weeks. Give you a proper comparison. But otherwise, they are alright, not going to tell you if it was worth the time and effort (remember I got new springs, valves, retainers, seals etc too, so that alone may offset the $200. Make up your own mind. Cheers
Thread Starter
Teching In
Joined: Jul 2017
Posts: 18
Likes: 0
Yeah I do, lots of them,
the best ones and even just good ones I particularly kept and got more data from, this one is a good one the night before I took the old heads off, it was a cool night an hour from the sun setting but it was a hot day, so the road was warm,
20m 2.01
100kph 3.77
100m 5.04
200m 7.65@153
300m 9.82
400m 11.78@189.5
.99g
110-180 5.9secs
thats probably the second fastest I had ever been, but close to the average numbers. Except the mph is down a little, usually the et would be 11.98 and the kph is 192.5, Note the g’s, (and sorry for metric, they are the same as your 60’, 330, etc)
new heads (and this is pretty much every result or atleast 0.04 within all et’s)
20m - 2.18
100kph - 4.02
100m - 5.28
200m - 7.88@155.6
300m - 10.04
400m - 11.98@192.6
Gs - .75
110-180=5.72
It is pretty much 0.2 secs slower in the 60ft, and then is the whole way
the best ones and even just good ones I particularly kept and got more data from, this one is a good one the night before I took the old heads off, it was a cool night an hour from the sun setting but it was a hot day, so the road was warm,
20m 2.01
100kph 3.77
100m 5.04
200m 7.65@153
300m 9.82
400m 11.78@189.5
.99g
110-180 5.9secs
thats probably the second fastest I had ever been, but close to the average numbers. Except the mph is down a little, usually the et would be 11.98 and the kph is 192.5, Note the g’s, (and sorry for metric, they are the same as your 60’, 330, etc)
new heads (and this is pretty much every result or atleast 0.04 within all et’s)
20m - 2.18
100kph - 4.02
100m - 5.28
200m - 7.88@155.6
300m - 10.04
400m - 11.98@192.6
Gs - .75
110-180=5.72
It is pretty much 0.2 secs slower in the 60ft, and then is the whole way
