Engine Temp on HP engine
Thread Starter
Instructor
Joined: Apr 2009
Posts: 175
Likes: 12
From: Jacksonville NC
Engine Temp on HP engine
I have fresh 383 stroker motor just built and dynoed 438hp/477tq with Quadrajet carb. Sounded grade on Dyno with no spark knock or anything. Install engine in car my 77 vette runs good very strong but when it gets over 180 temp it spark knocks only when secondary's open up and goes above 3900-4000 rpms. When engine is cool no issue at all. It has 041 heads, stock radiator, new clutch fan, stock ram horn mainifolds with true duals.
My question is, is it possible to make it stay cool under 180? If not what may be causing the issue?
34% timing
93 octane fuel with 108 booster
10.041 compression
Cold plugs, had hot plugs but changed
Auto/trans
355 rear
Factory chin molding
Factory fan shroud
160 thermostat
My question is, is it possible to make it stay cool under 180? If not what may be causing the issue?
34% timing
93 octane fuel with 108 booster
10.041 compression
Cold plugs, had hot plugs but changed
Auto/trans
355 rear
Factory chin molding
Factory fan shroud
160 thermostat
Last edited by edusmc1; Nov 7, 2016 at 09:38 PM.
Pro
Joined: Oct 2009
Posts: 664
Likes: 89
From: Marysville Ohio
Timing adjustment may be your only easy and cheap option short of a cam or head change. I think your compression is just a tad high for modern gas and older iron heads (less efficient chamber IMO). I don't know first-hand, but have read that the 041 heads are susceptible to ping with modern gas.
I would try just a couple of degrees and see how it runs.
I would try just a couple of degrees and see how it runs.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
When it was dyno'd it was using headers on the dyno and not the ram horn manifolds I'm guessing?
Corking up the exhaust by going through those ram horns could be creating a problem.
Have you tried using a different hanger or needles on the secondaries to enrichen the mixture?
Are you using CAI or under hood intake air?
Corking up the exhaust by going through those ram horns could be creating a problem.
Have you tried using a different hanger or needles on the secondaries to enrichen the mixture?
Are you using CAI or under hood intake air?
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I have fresh 383 stroker motor just built and dynoed 438hp/477tq with Quadrajet carb. Sounded grade on Dyno with no spark knock or anything. Install engine in car my 77 vette runs good very strong but when it gets over 180 temp it spark knocks only when secondary's open up and goes above 3900-4000 rpms. When engine is cool no issue at all. It has 041 heads, stock radiator, new clutch fan, stock ram horn mainifolds with true duals.
My question is, is it possible to make it stay cool under 180? If not what may be causing the issue?
34% timing
93 octane fuel with 108 booster
10.041 compression
Cold plugs, had hot plugs but changed
Auto/trans
355 rear
Factory chin molding
Factory fan shroud
160 thermostat
My question is, is it possible to make it stay cool under 180? If not what may be causing the issue?
34% timing
93 octane fuel with 108 booster
10.041 compression
Cold plugs, had hot plugs but changed
Auto/trans
355 rear
Factory chin molding
Factory fan shroud
160 thermostat
how did you get 10.041 C/R? What is your neg piston cc, head compressed gasket height, piston to deck, your heads should be 64 cc.
What is your total timing without the vac advance hooked up and what is the max advance with vac hooked up.
You have more than enough octane with just 93 and your temp is low. real performance and thermally efficient motors run in the low 200 degree range.. who ever talked you into 041 heads was not a friend. poor chamber design, pressed in rocker studs, very low flow even with 2.02/1.6 valves installed
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
If everything, ran fine, as you say, on the dyno. And now once installed in the car it isn't fine, I would tend to focus on the differences in the dyno environment vs the installed environment.
Has anything else changed since the dyno other than installation in the car?
I would agree with the opinion on the heads, but it is what it is unless more time and $$ are going to be spent to change it.
Has anything else changed since the dyno other than installation in the car?
I would agree with the opinion on the heads, but it is what it is unless more time and $$ are going to be spent to change it.
Last edited by REELAV8R; Nov 8, 2016 at 12:33 PM.
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Thread Starter
Instructor
Joined: Apr 2009
Posts: 175
Likes: 12
From: Jacksonville NC
Thread Starter
Instructor
Joined: Apr 2009
Posts: 175
Likes: 12
From: Jacksonville NC
When it was dyno'd it was using headers on the dyno and not the ram horn manifolds I'm guessing?
Corking up the exhaust by going through those ram horns could be creating a problem.
Have you tried using a different hanger or needles on the secondaries to enrichen the mixture?
Are you using CAI or under hood intake air?
Corking up the exhaust by going through those ram horns could be creating a problem.
Have you tried using a different hanger or needles on the secondaries to enrichen the mixture?
Are you using CAI or under hood intake air?
Thread Starter
Instructor
Joined: Apr 2009
Posts: 175
Likes: 12
From: Jacksonville NC
Thread Starter
Instructor
Joined: Apr 2009
Posts: 175
Likes: 12
From: Jacksonville NC
Since I'm not right in front of the motor, i'd like to ask a few basics.
how did you get 10.041 C/R? What is your neg piston cc, head compressed gasket height, piston to deck, your heads should be 64 cc.
What is your total timing without the vac advance hooked up and what is the max advance with vac hooked up.
You have more than enough octane with just 93 and your temp is low. real performance and thermally efficient motors run in the low 200 degree range.. who ever talked you into 041 heads was not a friend. poor chamber design, pressed in rocker studs, very low flow even with 2.02/1.6 valves installed
how did you get 10.041 C/R? What is your neg piston cc, head compressed gasket height, piston to deck, your heads should be 64 cc.
What is your total timing without the vac advance hooked up and what is the max advance with vac hooked up.
You have more than enough octane with just 93 and your temp is low. real performance and thermally efficient motors run in the low 200 degree range.. who ever talked you into 041 heads was not a friend. poor chamber design, pressed in rocker studs, very low flow even with 2.02/1.6 valves installed
I'm thinking after talking to you Gentelmen the headers is what I'm going to have to do! I appreciate you reading my post and helping.
Thread Starter
Instructor
Joined: Apr 2009
Posts: 175
Likes: 12
From: Jacksonville NC
Thread Starter
Instructor
Joined: Apr 2009
Posts: 175
Likes: 12
From: Jacksonville NC
Melting Slicks
Joined: Jun 2016
Posts: 2,979
Likes: 332
From: Woodinville WA
Summit painted steel headers are dirt cheap; FlowTech (Holley) coated can be had for $319 @ Advanced Auto with coupon. Headers will get you more torque, more hp, and 2 mpg better fuel economy.
Does your C3 have a cold air intake? With your CR on iron heads, you'll probably want a CAI of some kind. Per David Vizard each 8 degrees intake temperature drop will gain you the equivalent of 1 octane detonation resistance. -You'll get more power and more detonation resistance.
You could also retard your cam timing by a couple of degrees to delay your intake close event, which would reduce your dynamic compression ratio / cylinder pressure. You've got plenty of torque so you might as well trade some of it for more HP on the top-end and more detonation resistance.
Adam
Does your C3 have a cold air intake? With your CR on iron heads, you'll probably want a CAI of some kind. Per David Vizard each 8 degrees intake temperature drop will gain you the equivalent of 1 octane detonation resistance. -You'll get more power and more detonation resistance.
You could also retard your cam timing by a couple of degrees to delay your intake close event, which would reduce your dynamic compression ratio / cylinder pressure. You've got plenty of torque so you might as well trade some of it for more HP on the top-end and more detonation resistance.
Adam
Last edited by NewbVetteGuy; Nov 8, 2016 at 05:13 PM.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Tune was probably optimized to be used with headers putting in a colder plug lost me power...every motor has different needs though.
If it were me Id get an 02 sensor (check AEM at summit for example) in your collector and see what the car is doing;h opefully you can tune around it id think you could
Or if you dont mind the funds get a better radiator/fan combo and bring your running and air inlet temps down.
If you got a cool stat get a better fan (flame suit on)and put the clutch deal off to the side I hate those things
Not saying that is THE solution but you wont regret it for sure. Bigger motor/power means more heat needs more cooling capacity.
Sounds like youre happy with overall power shame someone talked you into dumping all that money into old iron heads.
Keep us posted
If it were me Id get an 02 sensor (check AEM at summit for example) in your collector and see what the car is doing;h opefully you can tune around it id think you could
Or if you dont mind the funds get a better radiator/fan combo and bring your running and air inlet temps down.
If you got a cool stat get a better fan (flame suit on)and put the clutch deal off to the side I hate those things
Not saying that is THE solution but you wont regret it for sure. Bigger motor/power means more heat needs more cooling capacity.
Sounds like youre happy with overall power shame someone talked you into dumping all that money into old iron heads.
Keep us posted
Last edited by cv67; Nov 8, 2016 at 07:10 PM.