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370 vs 408 N.A help

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Old 01-03-2020, 03:51 PM
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Default 370 vs 408 N.A help

Alright guys I just cant make a decision and I'm about ready to pull the trigger on an engine going with Thompson motorsport ,my goal is 500+whp daily drivable ish with ac etc in my 01 z28 6spd 4.10s , I if I cheap out and save the $900 ish and go 370ci how much power will I be missing out on compared to the 408 ? I have the fast 102 ported 243s with larger valves ,cant afford new heads so I have to run these .also TMS suggest a 238-242 113 cam which I think is small for a stroker ,but I do want it to drive nice in traffic ac on etc ,also I was told my 36lb injectors are sufficient but I also feel that they are small for 500+ hp and was told to get 42-46lb

Old 01-03-2020, 03:55 PM
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Seems reasonably you could be down 30-50hp with a 370 compared to a 408 and the same in torque. That cam will drive nice in a 408.
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Old 01-03-2020, 04:00 PM
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The stroker will put down more torque across a larger rpm spread. The fun factor will be higher.
yes, piston speed will increase but that is a fair trade off. (Just limit rpm )
Old 01-03-2020, 04:06 PM
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Contact Pat G for a cam.... thank me a later.
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Old 01-06-2020, 08:43 AM
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Power (HP) will be minimal between the two, Tq is where you will see the difference. You will have more usable HP/TQ with the 408. Let us know if we can help in any way. Thank you sir.

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Old 01-07-2020, 12:22 PM
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Originally Posted by thompson
Power (HP) will be minimal between the two, Tq is where you will see the difference. You will have more usable HP/TQ with the 408. Let us know if we can help in any way. Thank you sir.

Thank you,
Kyle
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I'll be given you guys a call real soon just coming up with the last few hundred I need
Old 01-07-2020, 03:46 PM
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Originally Posted by thompson
Power (HP) will be minimal between the two, Tq is where you will see the difference. You will have more usable HP/TQ with the 408. Let us know if we can help in any way. Thank you sir.

Thank you,
Kyle
972-853-2450
Yup. Your HP is going to be limited by the airflow of the heads. It takes X amount of air to make X amount of HP.
Old 01-07-2020, 10:12 PM
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You'd probably end up with more piston skirt wear on the 408 as the miles add up.
Old 01-07-2020, 10:44 PM
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I went through this last winter, and ended up staying stock stroke. In hind sight I wish I would have spent the extra money on a crank and built a 408.
Old 01-08-2020, 01:13 AM
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I'm really pleased so far with the iron 376 with just 853 heads I built for about 11.1:1 though I'm using much less cam so the tourqe is awesome at the stock cruising rpms,. That cam spec looks really big to me but I don't know anything
Old 01-08-2020, 07:47 AM
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Just my opinion, but if Im spending that kinda money, I will gladly spend the extra change and go with the stroker crank.
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Old 01-08-2020, 09:02 AM
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I vote for the stroker. The 408ci will make your goal of 500whp easier to achieve while maintaining better drivability than 370ci.
Old 01-08-2020, 11:47 AM
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No replacement for displacement!!! Go for the stroker. Torque is what makes things more fun.
Old 01-08-2020, 01:24 PM
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I'd favor the 408 over the 370. With Correct part selection and assembly the 4 inch stroke motor should hold up well. There was one 4 inch crank build that held up for 170,000+ miles and lots of fun.
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Old 01-08-2020, 02:05 PM
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Stock stroke cranks can be had for free so if it gets hurt at some point down the road it's going to cost a lot less to repair it or at that point if you had more funds you could make it a stroker, I'm thinking you would be happy with a flat top 370-376" and your heads but I'm on a tight budget so I wouldn't splurge on a fancy crank unless the rest of the car was setup ideal for it. N/a only though and no budget to worry about (your money) I'd do as much cid as possible for a weekend car
Old 01-08-2020, 02:26 PM
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408 with LS3 heads will be the better route Ive gotten 590+whp using the TMS/FED M311s before N/A (13.0:1CR)
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Old 01-08-2020, 06:39 PM
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Originally Posted by Tuskyz28
Contact Pat G for a cam.... thank me a later.
Probably the best $26.25 I ever spent.

CamMotion 238/246 .633/.633 111+3 on my Gen 3 LS370 build...
Old 01-08-2020, 07:02 PM
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Originally Posted by 01CamaroSSTx
Probably the best $26.25 I ever spent.

CamMotion 238/246 .633/.633 111+3 on my Gen 3 LS370 build...
He have to be the most knowledgeable cam guy I've spoken to....
Old 01-08-2020, 07:42 PM
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Yes! Or whatever fits your budget. Maybe the 370 with your 243s will make for a good combo. The 408 may need more flow if you want to take advantage of the extra cubic inches.
Old 01-08-2020, 09:08 PM
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Buy once and build once. Save up a few more hundred and do the stroker. Then start saving again to do the heads you want later.

But if you do the 370 now there is a good chance you will regret it. I doubt there will ever be a time that you go man I wish I had a 370 instead of a 408
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